What happens when a rogue state with a history of bellicose anti-American rhetoric acquires the ability to hit parts of the United States with a nuclear-tipped ballistic missile? Well, we’re about to find out.

On July 4, North Korea flight-tested its longest-range proven ballistic missile to date, claiming that it has developed an intercontinental ballistic missile (ICBM) capable of striking the United States. The United States ultimately confirmed North Korea’s claim after initially classifying the projectile as a “land-based, intermediate range ballistic missile (IRBM).” U.S. officials now say they believe North Korea successfully flight-tested an ICBM. The missile appears to be a two-stage liquid fuel design. Six months after President Donald Trump suggested on Twitter that a North Korean ICBM capability “won’t happen,” it appears that it has.

The consequences of what happened on July 4 are hard to exaggerate. The ICBM test is an important milestone in the overall development of North Korea’s nuclear and missile programs, and crystallizes several ongoing trends in its nuclear force development and strategy. The launch also fundamentally changes the nature of the threat posed by North Korea to the United States and its regional allies, handing the Trump administration a difficult problem it can no longer avoid.

What Is the Hwasong-14 ICBM?

It is difficult to overstate just how impressive North Korea’s technological advances have been, all while it has faced significant international pressure and sanctions on its program. A look at the specifics of the missile that was tested, as well as the developmental path it took, provides a sense of how rapidly North Korea has developed its capabilities compared to its peers.

The missile that North Korea is calling the Hwasong-14 flew to a range of 934 kilometers, reached an apogee of 2,802 kilometers, and was in the air for 37 minutes. It splashed down inside Japan’s 200-nautical-mile exclusive economic zone in the Sea of Japan, becoming the sixth North Korean missile to do so since a Nodong missile launch last year.

Given the range, apogee, and flight time, early open-source assessments estimate that the Hwasong-14’s full flight range capability is well in excess of the 5,500-kilometer cut-off that the United States uses for classifying ballistic missiles as “intercontinental.” (To avoid sending the missile over Japan, North Korea tested it on a lofted trajectory to shorten the overall range — nearly firing it straight up. By assuming a firing angle that would put the missile on a more standard trajectory, analysts can estimate a minimum demonstrated flight range.) David Wright of the Union of Concerned Scientists estimated a minimum demonstrated range of 6,700 kilometers, which would allow this missile to deliver a nuclear payload to population centers in Alaska and potentially reach Hawaii with a modified payload. The range could very well exceed 7,000 kilometers, which would bring Honolulu and the headquarters of U.S. Pacific Command within reach. John Schilling, another ballistic missile expert, estimates a “maximum range of perhaps 8,000 kilometers.”

North Korea’s own released images allow us to understand some details about the developmental path this particular ICBM may have taken. The “Hwasong-14” appears to be an entirely new missile that had never been seen before. It was not paraded at this year’s April 15 military parade for Kim Il-Sung’s 105th birth anniversary and it had not been seen at earlier parades.

However, the few images that have been released of the missile itself show features that are familiar to anyone who closely watched the May 14 launch of the Hwasong-12 IRBM. (That missile was North Korea’s longest-range missile to be successfully flight tested under the Hwasong-14.) The ICBM’s first stage appears similar to the Hwasong-12, suggesting that it may have been indeed a stepping stone toward this two-stage ICBM.

The Hwasong-14, like the -12, uses what appears to be a single large booster with four attached vernier engines for steering and does not use any grid fins or other control surfaces. The engines are liquid-fueled and appear mighty similar to the Hwasong-12’s engine, which in turn is similar to the so-called “March 18” liquid fuel engine. North Korea tested a liquid fuel engine on March 18 and ominously signaled that the “whole world will soon witness what eventful significance the great victory won today carries.” The Hwasong-12, and now the Hwasong -14, may have made it clear what Kim Jong-Un meant by that.

Another similarity is that the new ICBM uses a converted China-built 16-wheel WS-51200 truck converted into a transporter-erector. This is the second launch to use such a configuration after the Hwasong-12 IRBM test. The WS-51200 was first seen carrying the as-yet untested Hwasong-13 or KN-08 ICBM at a military parade in 2012.

In released imagery, the transporter-erector brings the missile to a launch area and erects it on to a static firing table. The launch takes place with the expensive transporter-erector clear of the launch area. It’s unclear whether this configuration is meant to protect the expensive converted Chinese logging trucks or if North Korea would endeavor to use such a configuration operationally.

Nevertheless, the use of a transporter-erector for now suggests a still-volatile system and would require significant time to fuel and prepare for first use. Indeed, sources claim the United States detected at least the first stage being fueled. By not preemptively destroying the missile or trying to intercept it, as some have advocated, the United States and the world have gathered valuable intelligence on what North Korea has developed, and how it tests and prepares the missile. North Korea had attempted to test two systems in October 2016, leading to two large explosions that open-source researchers were able to see in satellite imagery. It remains unclear if those were attempts at testing earlier iterations of the Hwasong-12 or Hwasong-14. (U.S. Strategic Command reported those tests as “presumed” Musudans, another North Korean liquid-fuel IRBM with shorter demonstrated range than the Hwasong-12.)

The Hwasong-14’s similarities with previously seen missiles end with its second stage and reentry vehicle, which appear to be total newcomers to the North Korean ballistic missile scene — and suggest that further development is on the way. Interestingly, North Korea tested a liquid-fuel engine on June 22 — less than two weeks before this launch — that was reportedly intended for the upper stage of an ICBM. It appears North Korea may have used that engine in the Hwasong-14 launch. The time between the tests would mimic the gap between the March 18 engine tests and the April 5 flight test attempt for the Hwasong-12 IRBM, which was a failure.

Significantly, North Korea appears to have had no trouble with stage separation and reentry with this launch, suggesting that its reentry vehicle technology is certainly good enough to allow for more ambitious ICBM development to longer ranges. Specifically, given the very high apogee for the Hwasong-14’s first test, the reentry vehicle likely experienced conditions in excess of normal ICBM reentry, in terms of both speed and temperature. This test will no doubt have given North Korean engineers valuable information on reentry vehicle survivability, penetration (to help defeat missile defenses), and precision that could be put toward future ICBM development.

This is innovation by necessity. After only several years of concerted development, North Korea has tested an ICBM — albeit a liquid fuel one that may not be the ideal responsive deterrent. By comparison, India, which has had an indigenous missile program for over three decades, has yet to successfully test an ICBM. Once derided as a joke of a program, the North Koreans have displayed a remarkable level of innovation and capability. And although the technological feat achieved by the Hwasong-14 is impressive, there is every reason to believe that it will not be the last surprise Pyongyang reveals to the world.

Indeed, there will be future ICBM development. North Korea has at least two ICBM prototypes in its inventory that represent different developmental paths toward a longer-range missile that could presumably deliver heavier payloads. As noted above, the new Hwasong-14 leaves much to be desired as a practical ICBM platform. North Korean engineers will be iterating and improving on this design while also pursuing parallel track development for other ICBMs. The July 4 test marks the start, not the end, of a new era in North Korea’s ballistic missile program.

The State of North Korea’s Ballistic Missile Program

The ICBM test itself has understandably dominated the headlines, but Kim’s strategy only becomes clear when we put this event in the context of the last few years: Since February 2017, North Korea has introduced and successfully flight-tested an entirely new suite of ballistic missiles. In the short-range (sub-1000 kilometer) class, we’ve seen the KN-18, or the Scud-C with a maneuverable reentry vehicle, introduced. A maneuverable reentry vehicle is important because it is designed — given sufficient intelligence, surveillance, and reconnaissance support — to hit moving targets, such as ships or aircraft carriers, in addition to defeating missile defenses. In the medium-range (1,000 to 2,000 kilometer) class, we’ve seen the Pukkuksong-2 solid-fuel missile introduced and entering mass production in May. In the intermediate-range class, we’ve seen the Hwasong-12 successfully flight tested. And now, North Korea has added an ICBM to its suite. It has also shown off a new coastal defense cruise missile launcher (the Kumsong-3) and declared initial operating capability for the Pongae-5 (KN-06) surface-to-air missile system.

If the message in 2016, when 24 ballistic missile tests and two nuclear tests were held, was that North Korea’s missile development is accelerating, the message in 2017 is that Kim is in hot pursuit of a diversified and capable operational nuclear force — North Korea’s own “full spectrum” deterrent. The addition of an ICBM to the mix is the most significant, but also the least surprising development. North Korea has signaled serious intent to acquire an ICBM since its first flight-test of the Taepodong-1 back in 1998, which led the United States to negotiate a missile-launch moratorium that would incidentally collapse on July 4, 2006. Second, in the past year and a half, Pyongyang has shown off advances in its missile nose cones and liquid-fuel engines that have steadily signaled that a successful flight test like the one we saw on July 4 was imminent. That North Korea eventually tested an ICBM is not a shock (though the speed with which it did so is certainly surprising). The real story is the diversity of North Korea’s nuclear-capable missiles, not just the ICBM but the shorter and medium-range missiles as well.

There is some good news. North Korea’s nuclear force ambitions will be constrained by its ability to procure adequate amounts of fissile material. North Korea watchers have been anticipating a sixth nuclear test for quite a while, and presume it is only a matter of time. The delay could signal difficulties on the warhead design or production side (or, to be fair, something else altogether). In other words, North Korea’s manufacturing capacity for new and ever-more advanced missiles may outpace its fissile material stockpiles and actual nuclear warhead development. Though estimates vary and North Korea hinted it is looking into composite pits for its nuclear bombs that combine plutonium and highly enriched uranium, it will likely still be constrained in its targeting choices due to stockpile limits.

Implications for North Korea’s Nuclear Strategy

What strategy does North Korea hope to develop with all these capabilities? The contours of North Korea’s nuclear strategy have been relatively clear at least since the so-called “maps of doom” were released, depicting a portfolio of regional military (soft counter-force) targets that would degrade the ability of the United States and its allies to mount and sustain conventional military options, as well as U.S. homeland targets that included a variety of military commands and population centers.

One of us has termed this an asymmetric escalation strategy — threatening to use nuclear weapons to defeat a conventional attack by “asymmetrically escalating” the conflict to the nuclear level. Under this strategy, the rationale for developing shorter and medium-range missiles that can defeat American and allied forces in theater is obvious. However, asymmetric escalation only avoids suicide if it can deter American nuclear retaliation, which requires the development of a capability to hold the American homeland at risk. Enter the need for the ICBM.

If this sounds familiar, it should. This is exactly Pakistan’s nuclear strategy against India (in addition to technological cooperation between Pakistan and North Korea, we are also seeing strategic mimicking). The difference is that Pakistan does not require ICBMs to hold its primary adversary, neighboring India, at risk. North Korea does. North Korea’s strategy was telegraphed well before it could be implemented: Use short-range nuclear capabilities to defeat a conventional invasion, and long-range ICBM capabilities to deter American nuclear retaliation by holding U.S. homeland targets at risk. On July 4, North Korea completed the puzzle when it demonstrated the credible (if unreliable) ability to hold targets in America (if not the continental United States) at risk.

Based on its deterrence strategy, we should not expect North Korea to stop with the Hwasong-14. Kim Jong-Un’s plan calls for longer-range capabilities than this, and North Korea tends to do what it says. Expect longer-range missiles to appear in the near future, including ones that can reach America’s eastern seaboard. Down the road, these may appear in larger numbers and with greater responsiveness, such as solid fuel missiles. We underestimate North Korea’s ability to develop the capabilities it needs at our own peril.

So what? North Korea was nuclear before, it is nuclear after. What’s the big deal? The big deal is that now the United States cannot threaten a conventional invasion of North Korea without risking direct nuclear attack on its homeland. Not only does this curtail American defense and deterrence options, it has significant implications for its allies in East Asia. North Korea’s ability to hold the U.S. homeland at risk cuts a knife through the credibility of American extended deterrence commitments to Japan and South Korea. With North Korea developing the ability to strike the United States, Seoul and Tokyo may soon wonder whether the United States would truly give up New York or Los Angeles for them — in other words, would the United States still respond in kind to a nuclear attack on an East Asian city if it meant provoking retaliation on U.S. soil?

Indeed, the core strategic implication of North Korea’s ICBM development is an old Cold War goodie known as “decoupling.” That is, Bonn, Paris, and London feared that with Soviet ICBMs pointed at the U.S. homeland, American security guarantees in continental Europe were not credible. It is one thing to expose American military forces forward deployed in theater; it is quite another to expose American population centers to nuclear retaliation. It is part of what motivated de Gaulle’s France to pursue an independent nuclear deterrent. As hard as it may be to deter Kim, reassuring our allies may now be even harder.

Policy Options for Dealing With an ICBM-Armed North Korea

What options does the United States now have to address the North Korean threat? Wishing the threat away or hoping it will dissipate on its own remains a fantasy, as it has been for some years now. Furthermore, so long as China fears North Korean collapse more than it fears the hermit kingdom’s nuclear weapons program, this is not a problem the United States can outsource to China. The introduction of a nuclear ICBM does little to change these realities. Reported efforts to slow the program, such as cyber interventions like the so-called “left of launch” strategy, coupled with “strategic patience,” have clearly not hobbled the pace of development sufficiently, and patience in Washington — particularly with Trump — appears to be running thin. And such efforts could, at best, only slow North Korea, certainly not stop or roll its program back.

The United States and regional partners thus have three fundamental policy options for facing down an ICBM-armed North Korea. The first is to pursue the destruction of North Korea’s new capability, i.e. a “bolt from the blue” hard counter-force strike. This would have to be a sudden strike, because giving any warning time would prompt Pyongyang to just use its nuclear weapons before it loses them. But make no mistake, this guarantees a war, and probably a nuclear war. Even if the United States could find, fix, and destroy all of North Korea’s nuclear weapons and delivery systems, Seoul would almost certainly suffer unacceptable damage through conventional firepower alone. And if the United States missed a couple nuclear systems, particularly those that North Korea has so doggedly tested to defeat missile defenses, they would certainly be used on whatever targets they could find. The window for thinking about disarming North Korea by force without guaranteeing millions of fatalities has probably long closed.

If the costs of a regional war are unacceptable, a second option is to practice deterrence and learn to live with an ICBM-armed North Korea. This option strikes us as the most realistic, though a very hard sell to allies whose appetite for reassurance extends beyond “we will just keep North Korea at bay with our military forces.” But at least for Washington, living with hundreds of ICBMs pointed at its territory is nothing new. A North Korean ICBM would be cause for unique concern if there were reason to believe either that Kim’s nuclear strategy was premised on a nuclear first strike against the U.S. homeland (it isn’t) or that Kim was irrational (he’s not). Practicing deterrence would presumably require heavier investment by the United States, South Korea, and Japan at the conventional level. It would also lead to continued investment in missile defense systems and counterforce capabilities, which could exacerbate North Korean insecurity and lead to a larger and larger North Korean arsenal. And in a crisis, deterrence could fail and option two could quickly bleed into option one. It is not hard for the United States to directly deter North Korea. But it is very hard to do that while also extending the deterrence that our allies want, without triggering an arms race.

The third option is to consider negotiating with North Korea. This approach has been tried before, both bilaterally and multilaterally, and has always been a difficult sell to those in the policymaking community, who correctly note that it is North Korea that has been consistently in the wrong for years now, carrying out ballistic missile tests and nuclear tests in violation of U.N. Security Council resolutions. Pyongyang also maintains little goodwill or trust with prospective interlocutors given its decision to violate the spirit of the 1994 U.S.-North Korea Agreed Framework by starting a clandestine uranium enrichment program and its refusal to recommit to denuclearization. Still, the Agreed Framework, despite its collapse in 2002, did succeed in delaying North Korea’s ultimate acquisition of the bomb by freezing its plutonium stockpile. If there’s a lesson to be learned from the agreement, it’s that negotiations can buy time, even with a dearth of trust between the United States and North Korea.

However, one new problem with negotiations that moots many of the conditions that allowed for a freeze deal like the Agreed Framework is that North Korea, by showing us a working ICBM, has upped the ante and gained considerable leverage in any future talks. North Korea would presumably acquiesce to a freeze on its ballistic missile and nuclear testing, but its demands for concessions can now grow credibly steeper. Any prospective agreement with North Korea would require explicit acceptance of their nuclear state status and significant rollbacks to the U.S. conventional military presence in the Northeast Asian theater, both of which are nonstarters for the United States.

There are thus no good options at the moment for addressing the North Korean threat, only bad ones and catastrophic ones. North Korea’s first successful flight test of an ICBM is a significant development that represents the culmination of years of research and development, but also the start of a new era in terms of how Pyongyang will think of its own capabilities and strategy. North Korean nuclear strategy, far from being irrational, was in fact predictable — states facing conventionally superior forces threatening to invade them have little choice but to seek first use capabilities to defeat a conventional attack, as well as long-range strategic nuclear systems to deter any subsequent nuclear retaliation. It is the only rationalizable nuclear strategy in an otherwise insane and paradoxical business. North Korea said it was going to do this, and it now has. This program is off to the races and the attending strategic dilemmas — how to deter North Korea, reassure U.S. allies, and defend the United States — can no longer be kicked down the road. The age of the North Korean ICBM is upon us and the Trump administration can no longer avoid this reality, thanks to an Independence Day fireworks display by Pyongyang.

Ankit Panda (@nktpnd) is a senior editor at The Diplomat and an independent researcher. Vipin Narang (@NarangVipin) is an associate professor of political science at the Massachusetts Institute of Technology.