President-elect Donald Trump has vowed to talk to North Korea and improve relations with Russia—the two countries which currently present the greatest challenges on nuclear security. If Trump is serious about pursuing these worthy goals, he must keep the Iran nuclear agreement. Apart from being disastrous in itself, scrapping the deal would doom any attempt by the Trump administration to engage Moscow and Pyongyang.

The Trump administration’s Iran policy will be key for North Korea, as it will constitute an important lesson for the latter about the benefits of diplomacy with the United States. North Korea might be isolated, but its leaders follow world news. And although they have little in common as countries, North Korea and Iran have long been targeted by a similar United States non-proliferation policy, characterized by demonization, coercion, and threats of regime change. That policy was also applied to Iraq and taken to the extreme with the 2003 war – a key factor that prompted North Korea to cross the nuclear threshold.  

The Obama administration tried to break from the coercive model with Iran, and instead opted for a diplomatic solution based on compromise. The change of strategy bore fruit in the form of the 2015 Iran nuclear accord. Although any deal with Pyongyang would look very different, this is certainly the direction that the United States should also pursue with North Korea. However, if North Korea sees that a nuclear deal sealed by one U.S. administration can simply be ripped apart by another administration, what incentive would it have to go down the same road? A United States failure to respect its commitments under the Iran accord would undermine its trustworthiness as a negotiating partner, effectively ruling out any diplomatic efforts with either Iran or North Korea.

As for Russia, it would not want to see the United States renege on the Iran agreement, to which Moscow is also a party. However, there is more at stake here than diplomatic courtesy: the agreement with Iran provides a unique opportunity for Trump to improve U.S.-Russian relations by addressing Putin’s long-standing concerns over U.S. missile defenses in Europe. The European missile defense project was initially justified in terms of Iran’s nuclear and missile programs. Russia has always suspected that this justification is an excuse, instead arguing that the system could undermine its nuclear deterrent. This was the case particularly with the Bush administration’s plans to deploy long-range interceptors in Eastern Europe. In 2009, the Obama administration introduced what seemed to be a more sensible plan, the European Phased Adaptive Approach, which subsequently became NATO policy. As President Obama argued at the time, European missile defenses were necessary only as far as Iran’s nuclear and missile programs posed a real threat.  

However, NATO’s anti-missile project entered a new phase in May, with groundbreaking of a new interceptor site in Poland—even though the nuclear deal has significantly reduced the risk of nuclear proliferation in Iran. Iran also does not have missiles of the range that would justify the system’s current expansion to Poland. As for arguments about a potential Iranian breakout or the generic threat of missile proliferation posed by other countries, they do not suffice as justifications for the Polish site, either.

Pointing to the disconnect between NATO policy and the situation in Iran, President Putin said in June that “This might mean that we were right when we suspected our partners of being insincere, of deceiving us with references to an alleged Iranian nuclear threat.” Russia has responded to the missile system by threatening European countries hosting missile defense components. Paradoxically, this has made Europeans even more determined to stick to their outdated plans, which they increasingly—and mistakenly—view as a buffer against Russia.

By halting construction at the unnecessary Polish site, the new administration could remove one of the biggest thorns in Putin’s side, thus improving U.S.-Russian relations and easing tensions in Europe. As a side-product, the US would save $630 million and be in a much better position to pursue new arms control talks with Russia. However, none of this is likely if the Iran deal unravels, as it would be much harder to justify limiting NATO’s anti-missile system in the context of a re-escalation of the Iranian nuclear crisis.

The Iran nuclear accord is therefore vital not only for its own sake, but because of its implications for the other two major nuclear challenges confronting the next administration. The choice is clear: trash the Iran deal and let other global crises fester. Or protect the Iran deal, and help solve three.  

Tytti Erästö, PhD, is the Roger L. Hale fellow at Ploughshares Fund, a global security foundation. She previously served as a Stanton nuclear security fellow and research fellow in the Managing the Atom and International Security Research programs at Harvard’s Belfer Center for Science and International Affairs, and was a visiting fellow at the Vienna Centre for Disarmament and Non-Proliferation.

Image: U.S. DOE via Wikimedia