Ukraine is a bad news story that is destined to get worse. In the midst of a tragedy, it will strike some as inappropriate to note that things could be worse. Nonetheless, pausing to recognize why they are not can remind us both of successes for which we should be thankful and of obligations we cannot forget.

In two words, the good news about Ukraine is: no nukes.

Unlike 1993, when two thousand strategic nuclear warheads sat atop ICBMs aimed at targets in the United States, today Ukraine has zero nuclear weapons. Four years ago, fifteen nuclear weapons worth of highly enriched uranium remained at risk at Ukrainian sites in Sevastopol and Kharkiv. Today, Ukraine is nuclear-weapons-material free.

U.S. initiatives that produced these results include the Nunn-Lugar Cooperative Threat Reduction Program that provided the wherewithal to persuade Ukrainian leaders to eliminate nuclear weapons, and a series of summits that have served as an action-forcing process for eliminating nuclear weapons-usable material. Both offer clues for President Obama and forty other heads of state who will meet in The Hague on Sunday for the third Nuclear Security Summit.

Last week when the chief of the Ukrainian navy switched allegiance from Ukraine to the Autonomous Republic of Crimea, I was reminded of the early months of the Clinton Administration when officers in Kiev were ripping epaulettes off their Soviet uniforms and swearing an oath to defend the newly-independent state of Ukraine. Despite the many similarities between then and now, we can be grateful for one decisive difference.

In 1993, the persons of interest were Strategic Rocket Forces officers serving in the chain-of-command between Moscow and a superpower nuclear arsenal stationed on the territory of a newly independent state. At the Pentagon, we analyzed in excruciating detail scenarios that began with Ukrainian attempts to seize operational control of the weapons—and ended in the deaths of millions of Americans. If, for example, Russia had found Ukraine on the cusp of mastering launch codes, its attack on the weapons could have triggered accidental launch of scores of missiles aimed at us.

Officially, the chain-of-command continued to run from the new President of Russia through communications and control systems to missile officers in Ukraine. Physically, however, the missiles, warheads, officers, and mechanisms for launching weapons resided on the territory of Ukraine. Moreover, the individuals who operated these systems now lived in houses owned by the government of Ukraine, received paychecks from the Ministry of Defense of Ukraine, and were subject to promotion or firing not by Moscow, but by Kiev.

The story of the Clinton administration’s strategy to work jointly with Russia and Ukraine to avoid crises while inducing, nudging, and squeezing the weapons out is told elsewhere.[1] In January, 1994, Presidents Clinton, Yeltsin and Kravchuk of Ukraine signed an agreement specifying that all nuclear weapons on Ukrainian soil would be returned to Russia. In an imaginative swap, the highly enriched uranium from the warheads was extracted, blended down to low enriched uranium, fabricated into fuel rods, and returned to Kiev for use in its nuclear power plant producing electricity. Recognizing the deep distrust between Ukraine and Russia, the U.S. served as guarantor of the exchange. In Budapest in December 1994, these arrangements were reaffirmed in a Memorandum on Security Assurances in which Russia and the U.S. pledged to respect the political independence and territorial integrity of Ukraine. Pursuant to these arrangements, by 1996, nuclear weapons had been zeroed out of Ukraine.

From the perspective of American national interests, the single most important fact about Ukraine today is that there is no way events there can trigger nuclear explosions here. Moreover, as we look forward to next week’s Summit, we should note what happened just two years ago at the second Nuclear Security Summit in Seoul. There, Viktor Yanukovych—recently-deposed President of Ukraine—stood up to announce that in the past two years, Ukraine had finally eliminated its fifteen nuclear weapons worth of nuclear-weapons material.

Those now coping with the current crisis should remember actions taken over the past two decades that prevented this becoming a nuclear crisis. And they should not forget commitments we made as part of the price for denuclearization. Fortunately, and rightly, the US refused to provide Ukraine a NATO Article 5 security guarantee. We did join Russia, however, in accepting obligations that Russia has now blatantly violated. If the U.S. and its European partners fail to make Russia pay a significant price for violating these commitments, how will we persuade additional states to eliminate nuclear weapons and materials?

[1] Talbott, Strobe. The Russia hand: A memoir of presidential diplomacy. Random House LLC, 2007.

Allison, Graham. “What Happened to the Soviet Superpower’s Nuclear Arsenal? Clues for the Nuclear Security Summit." Discussion Paper, Belfer Center for Science and International Affairs, Harvard Kennedy School, March 2012.

Graham Allison is Director of the Harvard Kennedy School’s Belfer Center for Science and International Affairs.