For many, North Korea’s fifth and largest underground nuclear test on September 9 near the village of Punggye-ri, along with the litany of varied ballistic missile tests carried out by the regime this year, serves as the latest frustrating example of being stuck between a military rock and a diplomatic hard place. 2016 has been a banner year for the North Korean nuclear program, leaving the world scrambling to find a suitable response.

Competing strategic interests have once again made the formation of such a response frustratingly difficult. While repeated DPRK nuclear and missile testing has greatly unsettled China, for instance, the status quo has not deteriorated to the point where the value of North Korea’s role as a strategic buffer is overridden by the recently heightened level of instability it brings. For South Korea, however, Pyongyang’s barreling path toward becoming an operationally capable nuclear weapons state has sparked fears that the extended deterrence provided by the American nuclear umbrella may not be as reliable as it once was, reigniting talk that South Korea needs its own, indigenously developed nuclear deterrent. Further nuclear proliferation on the Korean Peninsula would be highly detrimental to U.S. strategic interests.

The United States must reinforce the credibility of its security commitments to South Korea while simultaneously striving to find a way to coax Pyongyang out of what to many appears an intractable shell. As such, Washington finds itself in the delicate position of having to delineate policy positons that can contradict each other without much prompting. This inherently constrains America’s task of finding a balance between North Korea’s military/economic isolation and whatever room is left diplomatically.

After the DPRK’s fourth nuclear test in January and a slew of missile tests that clearly highlighted the North’s determined pursuit of strategic weaponry at the expense of all else, the United States and South Korea announced the deployment of the Terminal High-Altitude Area Defense (THAAD) missile defense system to the Korean Peninsula in 2017, over Chinese objections, to provide another powerful layer of protection for South Korea. The September 9 nuclear test and the ballistic missile tests that preceded it however, particularly the April 23 firing of an SLBM KN-11 missile, have raised worries that the coverage from one THAAD battery may not be enough.

Stanford’s Siegfried S. Hecker, director emeritus of the Los Alamos National Laboratory, has made the convincing case that the diplomatic track to denuclearizing the Korean Peninsula was derailed by the failure of the Six Party Talks in 2009 and the Obama administration’s inclination toward a policy of “strategic patience,” ultimately leading to a hardening of the North Korean position. Today, the centrality of nuclear weapons to the Kim Jong-Un’s regime is almost beyond dispute.

Certainly, the emphasis Pyongyang has placed on nuclear weapons development since the transition of power in 2011 is striking, to the point where many have concluded that North Korea will never voluntarily barter away its nuclear arsenal. Since taking power, the young North Korean leader has greatly accelerated the pace of his country’s nuclear program; the September 9 test was the third conducted under his reign. In that time, Kim has been explicit in linking the DPRK’s economic future to its status as a globally-recognized nuclear state, wrapping the two in the common conceptual frameworks of junche and byunjin. Kim put such a notion forth during his May 7 address to the 7th Congress of the Worker’s Party of Korea, where nuclear development was highlighted and framed as the protective layer that would permit the North Korean economy to finally flourish.

Similarly, years of international isolation have been wrapped in the rhetorical cloak of juche, an ideology of self-reliance used as a multigenerational effort by the North Korean leadership to convince its people of the need to stand alone from a hostile world. Meanwhile, North Korea’s future as a nuclear weapons state has been entrenched into the national constitution, the country has of course withdrawn from the Non-Proliferation Treaty (NPT), and the frequency of its nuclear and missile testing has increased, often accompanied by apocalyptic statements that threaten nuclear war with Washington and Seoul.

Meanwhile, roads to a diplomatic solution have long appeared closed off. Negotiations of all stripes have failed in the past, the lack of trust between Pyongyang and Washington is deep and mutual, and the North Korean leadership perhaps views the geopolitical landscape as less favorable for diplomacy than it once was. After all, previous rounds of substantive talks came before 2011, when Libyan dictator Muammar Gaddafi was toppled and killed by a populist uprising backed militarily by the United States; Gaddafi had surrendered his chemical weapons stocks to the United Nations after the U.S.-led invasion of Iraq convinced him that threats of WMD-use could lead to regime change, but that didn’t save him. For Pyongyang, this is the ultimate nightmare scenario. Examples of other non-NPT states acquiring nuclear arsenals only to be eventually welcomed into the international community, like India, Pakistan, or Israel, further reinforce what Pyongyang views as a double-standard.

All of this can quite understandably form the uncomfortable picture of an unstable regime hell bent on acquiring a survivable, operationally-ready deterrent that can hit the continental United States (CONUS). While North Korea likely remains several years away, at least, from successfully miniaturizing and mating a nuclear warhead to a long-range ballistic missile capable of striking the CONUS, the stepped up pace of nuclear and missile testing this year nonetheless indicates that the window for military action to neuter its nuclear program is closing. Hecker has stated unequivocally that the DPRK nuclear arsenal at present already serves as a sufficient deterrent. North Korea has undertaken a massive expansion of the Yongbyon Reactor Complex, to the point where, between its ability to produce the requisite levels of plutonium and highly-enriched uranium at facilities throughout the country, it likely has around 20 nuclear warheads, with the ability to produce seven more on an annual basis.

Removing the North Korean arsenal by force, especially in a scenario where regime change is not the objective, would require a flawless intelligence picture that is currently encumbered by the twin problems of not having a complete picture of the North Korean nuclear program while also not having true verification of how accurate the current one is; Given the diversified range of launch platforms Pyongyang could deliver a nuclear payload from, the success of an effort to remove the North Korean arsenal can only truly be assured by escalatory measures that foreclose the potential for a limited campaign. As North Korea expert Rodger Baker has articulated, Pyongyang is making a calculated gamble, taking advantage of the space created by looming American and South Korean presidential elections (Seoul is also just coming off parliamentary elections as well) to advance its nuclear program into the final stages of a deployable system for all the world to see.

The assumption that no amount of diplomacy can ever convince the DPRK to part with its nuclear deterrent, however, may have cracks in its foundation. On July 6, Pyongyang released a statement through a government spokesman outlining what appeared to be a redefinition of just what denuclearization means to North Korea, specifically, the nuclear disarmament of the entire Korean Peninsula. There is more nuance here than meets the eye, and amid the typical bluster that emanates out of state press offices in Pyongyang, it can be easy to see why much of it gets lost in translation. It is also true that Pyongyang’s tepid overtures, if they can even be called that, occurred just hours before the U.S. Treasury Department sanctioned Kim Jong Un for human rights abuses, and that much and more has transpired since July. The larger point is that while the military window for stopping North Korean nuclear ambitions is closing, the diplomatic one may not have been shut as tightly as once believed. No matter how distasteful, rebuilding the machinery for reliable lines of communication could be helpful in managing future disputes and wider regional stability. Looking to a future that involves a diversified and dispersed North Korean nuclear arsenal, which could one day include tactical bombs, such mechanisms could prove lifesaving if the status quo does not change before then.

This does not mean the September 9 detonation should go unanswered militarily, far from it. The recent overflights of South Korean territory by supersonic B-1B bombers out of America’s base in Guam, which did not feature nuclear-armed planes, was an important signal to allies. Other measures put forward, like strengthened restrictions on the employ of North Korean expatriate workers abroad or third party U.S. sanctions on Chinese companies that do business in the sale and trade of DPRK mineral exports like iron ore and coal, have their merits as well.

One possible measure not receiving an abundance of coverage is the deployment of a second THAAD battery to South Korea, both for forcing compliance and utility. While one such system undoubtedly provides South Korea with a more layered and reliable missile defense network, gaps in coverage and some uncertainty regarding interceptor efficiency remain depending on how far south prospective North Korean missiles are fired from. If, for instance, they were launched close to the DMZ from the North’s base near Wonson, a single THAAD battery’s defended footprint would not cover all of South Korea, and the system would likely be forced by proximity to intercept short-range missiles in their ascent phase, a capability it has yet to definitively prove. Two THAAD batteries would provide comprehensive coverage and improve interceptor efficiency, adding another protective layer to South Korean missile defense that is not only justified, but sends a powerful signal of resolve to a North Korean regime emboldened by the success of recent tests to the point of, as Hecker fears, changing the regional security landscape.

Any prospective deployment of another THAAD system would of course have to take domestic political considerations within South Korea into account, and there should be little doubt that China would be unhappy with another layer added to the U.S. missile defense architecture in the region. Trying to convince a Beijing that clearly prefers the maintenance of the status quo to play a more effective role in controlling Pyongyang, however, is just as clearly a process that has been outstripped by actual events. While THAAD has contributed to the rise of a more confrontational and anti-American strain of Chinese scholarly thought within China, the system is hardly a zero-sum calculation for Beijing. Once more we return to the theme of a strategic scenario devoid of clear policy prescriptions.

Another THAAD battery will hardly solve the North Korean missile threat, but it would help in countering what are emerging as truly concerning threats. On April 23, Pyongyang fired a submarine-launched KN-11 missile 30 meters before it blew up. Such a second-strike capability, if ever operationally ready, would elude and threaten a single THAAD battery; two would provide far more comprehensive coverage.

Meanwhile, there are other ways to reinforce and solidify the deterrence bond between Washington and Seoul; in the days following the September 9 nuclear test, reports surfaced that South Korea has been contemplating adding 20 fifth-generation multirole F-35A Joint Strike Fighters from manufacturer Lockheed Martin, in what would constitute a substantial upgrade to South Korean power projection capabilities, to its original purchase order. If the reports prove accurate, this should be prioritized and expedited, and Washington should simultaneously revisit its decision to withhold four of the 25 technologies Seoul was promised in that order to assist in the development of South Korea’s KF-X stealth fighter program.

There is no single solution to the North Korean nuclear problem, and the necessary mixture of diplomatic and military responses ensures that almost any response will be met with resistance somewhere. Any sort of substantive progress with Pyongyang, if and when it comes, is likely to be frustrating and halting, with outcomes that will leave few satisfied. Between the United States, South Korea, China, Russia, and Japan, all of whom have major stakes in the future of the Korean Peninsula, consensus will be anything but easy to reach. As a result, the policy options on the table for Washington are anything but clear.

The North Korean leadership sees the United States, unsurprisingly, as an existential threat, and because of that view, it is highly unlikely to rollback progress made on a nuclear deterrent that it sees as the key to both the security of its leadership and protection from external aggression. While that deterrent is not yet bulletproof, that scenario is coming closer. In the near term, policy should be framed around the principle of stopping further North Korean nuclear development more than denuclearization as a precondition to future talks while enhancing the U.S.-South Korean missile defense architecture as much as possible.