Recently, we found ourselves thinking about how unchallenged assumptions can prove deadly in wartime. We were talking about how both advocates and opponents of strategic bombing before World War II were absolutely certain that “the bomber will always get through” — that neither anti-aircraft fire nor fighter defenses could keep a heavily armed bomber fleet from destroying its target. Yet when war broke out, American heavy bombers flying daylight raids against Germany suffered such horrendous losses by the end of 1943 that U.S. airmen were forced to suspend their air offensive until they could develop and field long-range fighters for protection.

That led us to wonder: What convictions are so deeply embedded today in the U.S. military’s planning for the next war that they could lead to catastrophe if proven wrong?

We scribbled down our initial thoughts and reached out to a number of colleagues for their suggestions as well. Of the many ideas on our list, 10 assumptions stood out as the most potentially dangerous. To be fair, the services are starting to examine some of them and a number of them are already subjects of public debate. But they remain so deeply embedded in U.S. military planning that they could lead to disastrous battlefield results — and potentially overall defeat — if they are proved wrong. Here they are, in no particular order.

The U.S. military still knows how to fight a major war. The U.S. armed forces have not practiced full-scale field, fleet, and air operations against an advanced peer competitor since the end of the Cold War. Massive live exercises, such as the annual REFORGER exercise series in Germany, deployed as many as 125,000 troops, many of whom often trained in gas masks and full chemical protective garb. These massive wargames simply no longer exist. While computer simulations can replicate some of the demands these exercises place on staffs and commanders, they cannot substitute for actually deploying tens of thousands of troops across an ocean and then maneuvering and supplying them over hundreds of square miles of real terrain. Moreover, the live integration of large-scale air, land, and sea forces operating against a high-end adversary that were common facets of these legacy exercises rarely occur today. What would happen if the U.S. military has to relearn how to integrate the operations of large units across the joint force while under fire in the next war? The United States can protect its ground forces from air attack. U.S. ground forces have not been significantly attacked from the air since the Korean War, largely because the U.S. Air Force has rendered opposing air forces essentially inoperable in every conflict since then. Even if the Air Force can still establish air supremacy in future conflicts (an assumption that the Air Force is starting to question, though slowly), the skies may still be filled with powerful threats to ground forces — including long-range surface-to-surface missiles, cheap explosive-laden quadcopters, or AI-empowered autonomous drone swarms (think a malevolent version of the drones used in the opening ceremony of the 2018 Winter Olympics). How would U.S. land forces maneuver while under persistent deadly attack from the air? The U.S. Air Force will be able to fight effectively from contested bases. During the Cold War, the Air Force assumed its combat bases in Europe and the Pacific would face serious threats. Its units trained to repair cratered runways, built large numbers of hardened aircraft shelters, and practiced conducting high intensity operations under a range of degraded airfield conditions (including chemical contamination). Yet today, many of those capabilities have atrophied, and dangerous new threats have emerged. What would happen to forward-based air operations if theater combat bases can only operate at 75 percent effectiveness? At 50 percent? At 25 percent, or even less? How would that affect joint operations and the missions of the other services? Stealthy aircraft will remain stealthy. The United States has invested hundreds of billions of dollars on fighters and bombers that rely upon stealth to minimize their radar signatures. Nearly every new combat aircraft depends upon stealth to survive and operate against highly capable advanced fighters and a sophisticated enemy air defense network. Yet a number of emerging technologies, such as quantum radar and passive radar, may degrade the effectiveness of stealth, or even render it entirely ineffective. How would air operations be affected if some, or even all stealthy U.S. aircraft suddenly became visible? Aircraft carriers can be both effective and survivable. The increasing anti-access/area denial (A2/AD) capabilities of potential U.S. adversaries mean that aircraft carriers may not be effective and survivable at the same time. China’s DF-21 and DF-26 anti-ship ballistic missiles pose particularly lethal threats to carriers, with estimated ranges of more than 1300 miles and almost 2500 miles respectively. China is also developing a hypersonic glide vehicle that could threaten carriers and prove even more difficult to counter. Operating carriers inside the range of these new long-range weapons dramatically increases the risk of losing one, so they will need to operate from further out in order to be survivable. But the further out they go, the less effective they are — because their strike aircraft have limited ranges (about 1200 nautical miles round-trip for the new F-35C), and repeated air refueling increases their vulnerability. In future conflicts, would the U.S. Navy — and the nation’s political leaders — be willing to accept potentially catastrophic damage to aircraft carriers as the price of flying more sorties over the target? If not, how would keeping the carriers far away affect the conduct of naval and joint operations in the middle of a major war? U.S. submarines will remain undetectable. The Navy’s submarine force has long had a reputation as the “silent service” because of its supposedly invincible shield of invisibility. But the advent of new detection means — such as lower frequency active sonar and non-acoustic methods enabled by the use of big data — now threaten the invisibility that has enabled U.S. submarines to patrol the oceans with impunity. American submarines may soon find themselves at much greater risk of detection in the undersea littorals around the world, and emerging new technologies may make it hard for them to remain undetected even in the deepest parts of the ocean. How would that affect the conduct of naval and joint operations? And, worse yet, what would happen to the U.S. nuclear deterrent if the supposedly undetectable leg of the nuclear triad becomes observable? Amphibious operations remain viable. Successful amphibious operations rely upon secrecy and surprise, but it is becoming easier to detect naval combatants near shore and attack them with increasingly capable and widely available anti-ship missiles. Landing troops ashore exposes amphibious ships to attack as they disembark troops and equipment. With even non-state actors acquiring advanced anti-ship missiles, it simply may be too dangerous to keep amphibious ships within those ranges for the time required to support a landing. And in an era increasingly characterized by new technologies such as swarming autonomous drones, the entire idea of amphibious landings on an opposed shore may become a particularly deadly anachronism. The U.S. military can protect its air and sea logistics pipelines. The U.S. military’s forward presence around the world is now smaller than it has been at any time since World War II. Using force therefore requires the United States to project more combat power from the homeland than it has done in decades, and to sustain that combat power across very large oceans. In the air, the U.S. military has long relied on an unchallenged aluminum bridge of cargo planes and refueling tankers to transport troops, cargo, and combat aircraft from the United States to their destinations overseas. Any adversary in a future major war would be foolish to ignore these gaping vulnerabilities. These vital logistics lifelines could be quickly disrupted through conventional attacks or asymmetric threats launched from what appear to be commercial vessels (perhaps using the CLUB-K missile system, which is housed inside a standard commercial shipping container). How would the United States project and sustain power across the seas and through the air during such attacks? How much of the nation’s fighting force would be consumed protecting these essential arteries instead of fighting in the combat theater? Advanced U.S. weapons systems will operate effectively under wartime conditions. Many of today’s most sophisticated U.S. warfighting systems are exercised under peacetime conditions, without being exposed to the inevitable fog and friction of war. For example, Navy crews often know not only the dates of live fire missile exercises far in advance, but also when and where attacks will originate — enabling them to tweak their ship’s combat systems for peak performance. Land-based ballistic missile defense exercises follow a similar script. What would happen if these exquisite high-performance systems needed to operate with no advanced preparation in chaotic wartime environments? Would they be able to continue functioning amidst repeated attacks, and after inevitable battle damage? If not, how would joint operations continue? The U.S. military can keep its secrets. During World War II, the highly classified Magic and Ultra signals intelligence programs gave U.S. and British leaders detailed access to many Japanese and German war plans. In doing so, they played a key role in helping the Allies win the war. Today, extremely sensitive information about U.S. troop and logistics movements, operational maneuvers, and critical battlefield plans resides on the U.S. secret (SIPRNET) and the top secret (JWICS) secure computer networks. The U.S. military assumes that these systems are secure and that adversaries cannot see its most sensitive operational secrets. But that may be a dangerously naive assumption, given the many well-publicized breakdowns in U.S. cyber security (especially the publication of the NSA’s most sensitive hacking tools) and the immense efforts some potential adversaries are devoting to targeting U.S. networks. What if one or more of those adversaries already has, or develops, a well-concealed 21st century version of the Magic or Ultra programs? How would the military operate effectively — or even operate at all — if these most secret networks are compromised?

If any of these deeply embedded assumptions prove false during the next war — or, even worse, if many of them are — the effects could be both cascading and catastrophic to prospects for a U.S. victory. The opening days and weeks of that war would be incredibly bloody, and it is not at all clear that the U.S. military could adjust in time to avoid defeat. The U.S. military needs to take a close look now at these assumptions about how it would fight, and make sure that contingency plans exist for the ones that pose the most risks. Waiting until they are proven wrong during the next war will simply be too late.

Lt. Gen. David W. Barno, U.S. Army (Ret.) is a Distinguished Practitioner in Residence, and Dr. Nora Bensahel is a Distinguished Scholar in Residence, at the School of International Service at American University. They are also Contributing Editors at War on the Rocks, where their column appears monthly. Sign up for Barno and Bensahel’s Strategic Outpost newsletter to track their articles as well as their public events.

Image: U.S. Navy/Matthew Bookwalter