25,000 feet over the Pacific, two KC-46 tanker aircraft fought for their lives. A determined attack was under way as two regiments of MiG-35 interceptors rocketed through the sky toward them. As the MiGs came east at over a thousand miles per hour with heavy jamming support, American F-22 Raptor and Japanese F-3 Shinshin jets converged on the threat, filling the sky with missiles. It was not enough. When the MiGs got within 100 miles, the tanker aircraft stowed their booms and dove for the deck. The rest of the coalition fighters and strikers deep inside enemy territory would have to find a dry piece of ocean to ditch on during their flight back. For the first time the enemy had achieved air superiority over a major battlefield merely by eliminating a pair of logistics planes….*

America’s air dominance relies on a number of key components. Highly trained professionals, networked communications, precision guided weapons, combined with cyber capabilities, robotic systems, and space assets, among other technological advances, have given the U.S. significant advantages over its adversaries. However, fulfilling our national strategy to support allies, deter aggressors, and – when necessary – project power, has a fundamental but strategic requirement that we don’t explore enough: the availability of fuel whenever and wherever we need it. As a primary component of America’s arsenal, air power necessitates fuel, whether it is a domestically launched long-range bomber, a forward deployed tactical fighter, or even an unmanned aerial system. Adversaries can jam our communications or shoot down our satellites, and our aircraft will still fly; but cut off our fuel supplies and our squadrons will be grounded, or worse, flameout. Consequently, the aerial refueling tanker force is a strategic asset and potentially a strategic vulnerability.

Unfortunately, limited attention is given to this vital logistics matter, most notably how two factors are combining to undercut our strategy to maintain a credible conventional deterrent and a decisive power projection capability. The first is self-imposed range limitations due to the fuel constraints of our tactical strike and fighter aircraft. Meanwhile, advanced threat systems continue to expand operating ranges, widening contested air space and posing a greater threat to bases. The combination of our current and planned aircraft’s range limitations and advanced threat systems may prove to be a key challenge to U.S. success in any future operating environment.

Theorists may attempt to cleanly cut military efforts into sharply defined tactical, operational, and strategic levels. The reality is that these layers overlap, each one affecting the other. While details like range and refueling can be dismissed as insignificant tactical or operational concerns, overall U.S. national strategy is built on the capability and capacity of our air power to execute at the operational and tactical levels. And at those levels, range and refueling are anything but mere details. Consequently, the elimination of an airborne tanker could have detrimental tactical implications. The cumulative effect of unavailable fuel and refueling assets at the tactical level could result in operational failure. And the inability to conduct operations in a particular region due to fuel constraints could turn America’s military strategy into a dead letter. Hence, the significance of fuel and refueling must be better addressed in U.S. strategic planning.

A2/AD, the WEZ Pushback, and the Range Problem

Great attention has been paid to the concept known as anti-access/area denial (A2/AD). A2/AD is the acronym-du-jour that consumes future warfighting concerns. But confronting a weapon seeking to bar access or traversing a denied area is nothing new. Francis Gary Powers, whose U-2 spy plane was shot down over the USSR in 1960, could testify that A2/AD has been around for decades. By definition, the Soviet Union’s V-75 Dvina, better known by NATO countries as the SA-2 Guideline, was an anti-access weapon designed back in the 1950s and used to deny area to enemy aircraft.

In order to access these contested environments in the past, American tacticians developed a number of ways to counter the threats. Aircraft could circumnavigate the fixed surface-to-air missile launch sites at safe distances, fly below the radar, take advantage of speed and maneuverability to overfly systems at high altitudes or coordinate electronic jamming. They could also deploy expendable decoys, fire weapons, or hide behind technologically advanced structural designs and surface coatings.

So how is the modern A2/AD environment any different, and why is it such a great concern for American military strategists and tacticians alike? The answer is range; or to use a cliché, the tyranny of distance. The new generation of A2/AD systems incorporate integrated technology, advanced processing, accurate navigation, precision targeting, and coordinated systems to build layers of defense-in-depth. Modern day A2/AD is designed to push safe operating areas so far away that intended target areas cannot be reached, despite our own sophisticated platforms and weapons. These advanced threats include surface-to-air missiles, land attack cruise missiles, anti-ship cruise missiles, and long-range missile-bearing fighters. Weapons engagement zones (WEZ), the geometric sphere of airspace in which weapons can launch and hit their intended targets, have grown from a few miles to a distance so vast it may extend beyond the combat radii of many current tactical assets. Even if our strike and fighter aircraft are stealthy enough to individually trespass towards a target undetected, they may be forced to launch from distances that will challenge their ability simply to reach it (See “China’s new drone will hunt stealth aircraft“).

To influence an adversary, we must be able to survive these threats. The safe option is to provide deterrence while remaining outside of the threat WEZ, with the intent of overcoming the distance if combat operations are required. Unfortunately, forcing that option upon us is the ultimate goal of the A2/AD effort. By pushing our forces so far away, an adversary limits our ability to respond in a timely manner to any crisis, as well as give them advanced warnings if and when we do respond. In some cases, this time-distance factor may entirely prevent our ability to respond effectively.

Presently, the estimated combat radius of our most advanced fighters , including the fifth generation we are set to buy, is just over 600 nautical miles. The problem is that the projected range of many of the new advanced threats to our basing options, ashore and afloat, far exceeds that distance, with current threats assessed at 800 nautical miles and projections of future capabilities in excess of 1,000 nautical miles. Without external aerial refueling options, staying outside the threat WEZ means our fighter aircraft cannot reach their intended targets.

One answer is to try to operate with presumed impunity inside the WEZ. We can base our fighters or steam our aircraft carriers well inside the threat ranges of these new advanced threats and rely on imperfect defensive measures to protect these assets. In peacetime, this has been a standard practice to meet alliance commitments and monitor the global commons. Even in times of potential conflict, our forces have navigated inside threat zones to show political resolve, relying on deterrence to thwart any danger. Rather than add to the hype of A2/AD, the Chief of Naval Operations refers to this operating environment as “assured joint access.” However, this does not eliminate the risks; instead, the risk is accepted as an unprovoked attack is deemed an unlikely occurrence. The problem is that if a situation escalates to an actual fight, our risk calculus may change. We can rely on integrated air and missile defenses, continue developing defensive countermeasures, or leverage distributed basing strategies and mobile naval vessels to complicate an enemy’s targeting plan, but the risk remains.

In a study by the Center for Strategic and Budgetary Assessments (CSBA), retired Air Force Lt. Gen. David Deptula and analyst Mark Gunzinger note that air bases may be vulnerable to precision-guided missiles and aircraft may not be able to enter hostile airspace without risking attrition. Specifically referring to naval options, they write, “…the wisdom of deploying carriers within range of anti-ship ballistic and cruise missiles so their short-range fighters can reach their objective areas is doubtful at best.” As a result, the study concludes that enemy anti-ship ballistic and cruise missiles supported by space-based sensors and long-range surveillance aircraft may force aircraft carriers to operate 1,000 miles or more offshore, well beyond the 600 mile range of our most numerous strike fighters.

Just as with naval strike forces, a variety of factors may push U.S. land-based fighters outside of the 1,000 mile range noted before. Many of our forward bases in allied countries fall within such a weapons radius may be directly threatened, limiting or preventing the launch and recovery of aircraft. In a speech at the Navy League’s 2014 Sea-Air-Space Exposition in National Harbor, MD, the Chief of Naval Operations noted that these concerns have compelled the U.S. Pacific Command to consider hardening measures to protect such facilities. These are designed to mitigate the damage of an attack on the base, not eliminate it.

Exacerbating this physical limit are diplomatic restrictions that can inhibit our ability to fly from allied basing. In the late 1990s, the Air Force decided to relocate its command and control Combined Air Operations Center air base to Qatar after Saudi Arabia refused to allow us access to bases.

Another concern also remains, regardless of how we try to navigate the risk to our bases. Unless targets are in the littoral or border regions and our aircraft are launching from ships directly off the coast or hosted air bases along a border, refueling will still be necessary to ensure that tactical air assets have sufficient reserves to fight their way through hostile airspace. If targets lie in the deep strike realm well inside sovereign boundaries, then inflight refueling will be the critical node to enable mission success regardless of where a sortie launch originates.

Therefore, extending the reach of our tactical fighters is critical to the credibility of our power projection, the ability to effectively deter a hostile adversary, and thus to the execution of our strategy.

Plus the Enemy Can Reach Out: Tanking in Harm’s Way

Even in a benign environment, aerial refueling is challenging. Flying two aircraft so close to each other that there is an intentional mid-air collision, albeit a gentle one, can be unsettling. More unnerving for a pilot, though, is staring at empty fuel indicators with flashing low fuel lights and hearing bingo warnings. As difficult as aerial refueling is, U.S. air supremacy during the past decade at least enabled aerial refueling without ever having to factor in the threat of adversary air defenses. Future threat systems may change that paradigm.

It is important to understand that a threat doesn’t have to be realized to matter. As Robert Farley writes “anti-access strategies need not threaten to completely destroy an attacker; effective deterrence can threaten simply to destroy enough aircraft to significantly damage an enemy’s air force.” An anti-access strategy could thwart an attacker by merely putting at risk a limited number of key assets rather than needing to win an overall war of attrition.

The United States has gone to great lengths and expense to develop the new generation advanced stealthy strike fighters. Yet, even if U.S. military forces possess more formidable and survivable tactical aircraft, the clever anti-access strategist will simply seek an alternative target to disrupt the American advantage.

So what is the weakest link in America’s kill chain? In the past, it was the EA-6 Prowler electronic attack platform. With no air-to-air capabilities, limited maneuverability and situational awareness when conducting jamming missions, and limited speed to outrun a fighter, the plane was relatively vulnerable. But it was crucial to the success of an entire air strike package (the massing of coordinated fighters and bombers collectively attacking adversary targets in a denied area), as all the other fighter and attack aircraft depended on it to face surface-to-air threats. Trying to take on an entire strike package would be a monumental challenge, but if one aggressor could leak through the wall of fighters and eliminate the jamming platform, strike forces would be exposed and forced to abort the mission.

To protect the vital jamming missions of the EA-6, dedicated fighter escorts were assigned to protect it. Loitering behind the strike package, these fighters were tied to the Prowler, to intercept any adversary aircraft that managed to evade the fighter sweep clearing the path. The EA-6 was an operational necessity and consequently a strategic asset as well as a strategic vulnerability.

In more recent years, this threat was mitigated by the replacement of the EA-6 with the EA-18 Growler, a modified variant of the FA-18 Super Hornet that can defend itself with air-to-air capabilities while conducting electronic attack missions. Similarly, electronic attack capable aircraft such as the F-16CJ and individual payload jamming pods mounted on fighters can provide electronic protection on more survivable aircraft than the Prowler. This is good news for the electronic attack role. But another weak link remains in the kill chain.

Given the vast ranges predicted to define future contested airspaces, the new strategic vulnerability, and therefore the new high value asset, may be the airborne refueling tanker. While an adversary may not be able to challenge our fighters for air superiority in the near future, our growing reliance on tankers to sustain that superiority makes them prized targets.

According to Air Force contingency operational planning, baseline plans for any regional conflicts call for an approximate capacity of 200 aerial refueling tankers. With 200 assets, it is tempting to view the risks to any single tanker aircraft as an acceptable cost of battle. But what if losing that logistics aircraft results in the flameout of a dozen other aircraft expecting to rendezvous with the tanker on their precarious return from a distant strike?

The tanker historically had the luxury of range and defense-in-depth to remain well behind the forward edge of the battle area. However, the combination of short-range tactical assets and a suite of new advanced threats that may be able to reach out and touch our logistics tail means this old assumption must be questioned.

Many experts surmise that newly emerging aircraft now being developed by potential U.S. adversaries have leveraged stealth technology and advanced designs, making detection by our early warning systems more difficult. Additionally, specifications with larger fuel capacity may allow them to fly a combat radius over 1,000 miles without refueling. Finally, these have been armed with a new generation of very long-range air-to-air missiles, some with ranges publicly reported to be 80 to even 200 miles. Such aircraft could threaten areas beyond sovereign borders as well as far out to sea.

In addition to potential adversary air assets, many nations are building up significant naval capabilities. Their ship-launched surface-to-air missiles expand the threat ranges well beyond coastal limitations. Not only may tanker aircraft no longer enjoy the safe haven of operating many miles away from danger, but additional threats may be floating directly beneath them.

The risk of an advanced adversary targeting the land and sea bases of our aircraft has gotten much attention in American defense circles. But, regardless of the success or failure of that effort, the combination of our short range and extended threats to tankers could still push our operations beyond the range needed for victory. Provided advanced warning, a tanker aircraft can run from an adversary fighter. In doing so, however, it abandons the friendly fighters it is supporting. This is the difference with command and control aircraft and electronic warfare aircraft compared to tankers. They can retrograde to maximum coverage ranges (distances permitting bare-minimum coverage at the extent of their systems’ employment limits) or simply turn and flee, leaving strike and fighter aircraft uncovered but still flying. But the tanker has to remain on station to provide a bridge for any range shortfalls. If their required tankers get shot down or are simply forced to abort the mission and bug-out, their supported fighters will also have to abort or simply not make it home.

Rethinking Refueling and Preserving our Kill Chain

The threat to our tankers is something that has been understood, but is not being addressed at a sufficient level. The KC-46 is the long-awaited tanker replacement for the aging KC-10, KC-130, and KC-135 platforms. But it won’t solve the above problems.

In the future operating environment, contested airspace will expand to cover such a large range that tankers may be required to encroach into unknown threat envelopes to provide the necessary fuel for strike and fighter aircraft to achieve mission demands. This bridging measure may expose tankers to significantly greater threats than envisioned when the KC-46 was conceptualized.

As part of the requirements process in its development, the KC-46 was conceived with “the ability to detect, avoid, defeat and survive threats using multiple layers of protection” that “will allow the KC-46 to operate safely in medium-threat environments.” Yet consider what would happen if the tanker finds itself in a high-threat environment because adversary systems can now reach what was previously considered sanctuary airspace. Will its “enhanced survivability – new robust defensive systems and cockpit armor protection” be sufficient to survive advanced surface-to-air weapons and air-to-air weapons that directly threaten more maneuverable fighter aircraft designed for the high-threat environment? The answer is no.

According to unclassified official reporting,** the KC-46 will have greater situational awareness of adversary systems via networked data links as well as threat detection from radio frequency warning receivers identifying the signals of threat RADAR systems. These will allow the tanker to get a head start in its bug-out should it find itself in a dangerous situation, thus ceding this critical air space to the enemy. Furthermore, it will have infrared defeating systems should it have to execute countermeasures against IR missiles.

These systems may allow the tanker to survive the medium-threat environment and even take evasive action before it trundles into a high-threat environment. But relative to the maneuverability of a tactical fighter, the KC-46 will have a challenging flight if it finds itself being targeted by an adversary fighter or many of the new surface to air missiles. Shot down or forced to flee, the effect on the rest of the US operation supported by it would be the same.

The United States can and must better plan and equip its forces to address the changing operating environment created by this tyranny of distance and enemy gains in reach. Among the concepts it must prioritize are:

1. Increase survivability of airborne refueling tanker aircraft. As a stop-gap measure, aerial refueling tankers will have to become even more survivable. No add-on features will turn a KC-46 into a fighter, but externally mounted electronic protection systems such as advanced self-protection radar jammers and advanced expendables can provide additional countermeasures to defeat RADAR missiles in addition to the IR systems already considered in the program of record. But these must be understood as limited gains, not sold as solutions. Unfortunately, even enhanced defensive systems will never fully thwart an adversary fighter or missile attack.

2. Plan for defense of tanker aircraft in the same manner as other high value airborne assets. The defense of tankers needs the same level of planning and effort as the defenses previously afforded to high value assets like the electronic attack platforms. While air forces are adjusting operational concepts to address greater threats, the specific defense of tankers has not received the attention it warrants. Planners must accept that the air supremacy (total ownership of the airspace) enjoyed by U.S. forces in the recent past is unlikely in a contested future. Pragmatists are refining tactics, techniques, and procedures to operate in a realm of localized air superiority utilizing fighters to temporarily dominate a limited space, providing a general defense for all operating aircraft in that space. Unfortunately, a counter air mission to defend an entire strike package may be insufficient to ensure a critical tanker does not vacate its mission.

One concept that needs deeper exploration is a High Value Asset Combat Air Patrol (HVACAP). Because a tanker cannot flee without risking the fuel starvation of forward fighters, the tankers will need to remain on-station. This may require fighter escorts flying dedicated protection patrols to intercept adversary aircraft that may penetrate a fighter sweep. Just as a HVACAP ensured an EA-6 could continue its electronic attack mission when forward fighters were in threat envelopes, so too will a High Value Airborne Asset Protection fighter escort can ensure that the tanker can loiter within a high-threat environment to provide limited range strike/fighters with fuel. Both the Air Force’s and Navy’s most advanced air warfare tactics institutions are beginning to wrestle with this dilemma.

This HVACAP concept holds promise, but, in turn, it creates new requirements that need to be woven into existing operational, strategic, and even acquisition plans. Put simply, these were built upon different assumptions of the number of fighters available, the threats they would face, and how they would be used. U.S. air forces already face a looming shortfall in strike and fighter aircraft based on contemporary mission requirements as legacy fourth generation aircraft are replaced by a lesser number of fifth generation fighters. The potential need for even greater mission requirements will stress this shortfall even more.

Additionally, from the maritime domain, Navy Integrated Fire Control Counter-Air can augment defense of airborne aerial refueling tankers with additional platforms beyond just fighter escorts. While big-wing tankers are not an organic part of the carrier strike group, integration of ship based anti-air missile launch capabilities should be re-conceptualized to help defend this key operational enabler and strategic asset. Notably, this Air Force-Navy teaming is a perfect example of the kind of cross-service cooperation originally envisioned in the Air Sea Battle concept.

3. Incorporate tactical airborne refueling connectors. Due to the space constraints of aircraft carriers, the Navy relies on smaller aircraft to conduct inflight refueling during organic missions (independent missions conducted exclusively with aircraft from an aircraft carrier). In the past, these tankers had limited self-defense capabilities, relying on the same sanctuaries as the Air Force big-wing tankers, both flying in permissive airspace well behind enemy engagement zones. However, with the retirement of the S-3, the Navy incorporated aerial refueling into the FA-18 Super Hornet’s multi-mission capabilities. Now the Navy’s only organic tanker has the added benefit of being a fighter. Forces could keep big-wing tankers outside of greater threat ranges and use FA-18s to provide tactical tankers that could safely maneuver into high-threat envelopes. The fighter/tanker concept would provide critical interim tanking for other stealthier strike/fighter aircraft conducting combat missions deeper into contested airspace beyond the limits of their combat radii. These fighter/tankers could provide the necessary top-off of fuel during initial entry into a potentially dangerous airspace and the vital connection between low-fuel strike/fighters and the large tankers flying outside of contested airspace on their return to base or ship. Flying this connector role, the Super Hornets could also provide an additional layer of defense-in-depth in the same manner as the previously mentioned High Value Airborne Asset Protection mission.

4. Develop tactical airborne refueling connectors leveraging unmanned aerial systems. Unmanned aerial systems could also serve as these possible connectors. Drones used as mini-tankers could provide the same linkage as the Super Hornet, but with the advantage of not risking human lives and having longer duration on station. Taking this mission a step further, stealthy versions of these drones could also deliver their fuel payload and then continue into the threat environment, complicating adversary air defenses. Therefore ability not just to refuel, but to refuel another plane should be woven into future testing and acquisition priorities of unmanned systems, such as the Unmanned Carrier-Launched Airborne Surveillance and Strike (UCLASS) aerial system.

5. Requests for proposals for the next air systems should address both combat capability and radius to achieve the necessary reach. This problem is, in many ways, self-imposed. Our attack aircraft have insufficient range. The next generation of aircraft should not suffer from this problem.

Current manned tactical fighters may have the combat systems to fight the future threat but may not have the needed combat radii to properly deal with the array of anticipated threats in future contested airspace. The next aircraft acquisition coincidentally happens to be an unmanned variant with the potential for greater range limits. The Department of Defense can leverage the current development and contract process for the UCLASS to begin building the next generation fighter, stealthy, unmanned strike/fighter aircraft with the combat radius to achieve the necessary reach that the current inventory of fourth and fifth generation fighters fails to achieve. This may fly in the face of all military pilots who pride themselves on actually leaving terra firma strapped to an ejection seat. But if the current inventory lacks the reach necessary in the future, pilots must swallow their pride and ensure that the next acquisition meets the range requirements as dictated by the future threat.

As a comparative baseline for fuel capacity, there is a tradeoff between a manned cockpit and additional fuel tanks. To illustrate, just by carrying one less ejection seat, human body weight etc., the single-seat FA-18E carries approximately 1,000 pounds of of additional fuel (or 150 gallons) in comparison to the two-seat FA-18F. With the removal of all associated human interfaces (oxygen system, cockpit pressurization and environmental system, pilot-to-aircraft flight control hardware, etc.) additional fuel capacity would be even greater than 1,000 pounds for the same size airframe. And with a lower specific fuel consumption rate in unmanned aerial vehicles, this additional fuel translates to significantly longer flights. Without drastically affecting the shape and size of current systems deployed aboard an aircraft carrier, designing the UCLASS to meet the combat capabilities of fifth generation strike fighters while additionally achieving a far greater reach is an attainable goal.

The good news is that it appears that the U.S. Navy recognizes this opportunity. According to a UCLASS requirements officer, the Navy has defined its minimum strike range for the UCLASS at more than three times the combat radii of its current strike/fighters. Should the official RFP adhere to this range requirement while ensuring low observable characteristics and electro-magnetic spectrum management beyond current fifth generation aircraft, the UCLASS will be a formidable deterrent and power projection vehicle able to overcome the challenges of future contested airspace. Similar planning should be incorporated into Air Force acquisition plans.

The U.S. military faces a problem of changing operating environments and simple math. The present day evolution of advanced strike/fighter aircraft, commonly referred to as “fifth generation,” was envisioned decades ago before the current inventory of threats materialized. As the joint military services develop air power tactics to assure access into denied battle spaces, the limits of the current inventory of strike/fighter assets coupled with the vulnerabilities of aerial refueling tankers inevitably lead to a simple conclusion: Just as the U.S. strategy has begun to acknowledge the new array of potential threats to our overseas bases and ships, both the increased need for airborne tankers and the expanded threat sphere to those tankers must be factored into risk planning.

Absorbing these lessons, the Department of Defense needs to build a robust, survivable, long-range air power inventory designed across the full spectrum of combat operations to exploit contested airspace. The military services should evaluate the current shortcomings and risks to our fifth generation strike/fighters in contested environments and set the requirements for the next generation of manned and unmanned systems to ensure those gaps are addressed.

The exciting debates in the fields of space, cyber, robotics, stealth, information technologies, and exploitation of the electro-magnetic spectrum frequently overlook the vital and enduring necessity of logistics. Until the military services acquire an inventory of longer-range strike/fighters, fuel and the assured ability to inflight refuel in contested airspace will be the critical node, and a potential critical point of failure, to executing U.S. strategy. We are in the midst of gaining the fifth generation technologies and capabilities to conduct the next fight. But we have to be able to get there if we want to win it.

* This section was inspired from a scene in Tom Clancy’s Red Storm Rising, just updated with new systems and replacing AWACs with Tankers.

** Key Performance Parameters approved by the Joint Requirements Oversight Council in the Capability Development Document

Commander Greg Knepper is a Naval Aviator, with operational experience in both the F-14 Tomcat and FA-18 Hornet, and presently a Strategist in the Strategy and Policy Directorate on the Chief of Naval Operations Staff. Prior to joining the OPNAV Staff, he was a Federal Executive Fellow at the Brookings Institution in the Center for 21st Century Security and Intelligence (21CSI).

Peter W. Singer is Strategist for the New America Foundation and the author of multiple books, including Cybersecurity and Cyberwar: What Everyone Needs to Know and the upcoming Ghost Fleet: A Novel of the Next World War (June 2015) www.ghostfleetbook.com.