Nearly 70 years ago, a group of Manhattan Project scientists, having seen the power of nuclear destruction, created what they called the “Doomsday Clock.” It was a mechanism designed to warn the world of how imminent the threat of global catastrophe was becoming — the closer the clock moved to midnight, the closer we were to doomsday. Last month, the group of Nobel laureates charged with maintaining the clock changed its time to 11:57 p.m., denoting the closest we’ve been to doomsday in more than 30 years. Their reasoning is based not just on the world’s inaction on issues like climate change, but its provocative march toward a new Cold War.

Indeed, as catastrophe engulfs eastern Ukraine, the United States continues to stoke tensions with Russia, most recently by considering providing lethal weapons assistance to the government in Kiev. The potential move is supported by a bipartisan chorus of hawkish voices, led by Sen. John McCain (R-Ariz.) and including, it appears, President Obama’s soon-to-be secretary of defense. At his confirmation hearing last week, nominee Ashton Carter testified that he is “very much inclined” to support arms transfers, saying, “We need to support the Ukrainians in defending themselves.”

But arming the Ukrainian military is not in the best interest of the United States, nor is it in the best interest of Ukraine. It will only worsen a bloody crisis that has already claimed thousands of victims. As I have argued in the past, there is no military solution to this conflict, only a political one; and a new supply of U.S. arms will provide ammunition for Russian leaders who believe, fairly or not, that America is attempting to turn Ukraine into a military base near Russia’s borders. Indeed, as Jeremy Shapiro of the Brookings Institution writes, “If U.S.-provided weapons fail to induce a Russian retreat in Ukraine and instead cause an escalation of the war” — which they almost certainly will — “the net result will not be peace and compromise.”

Rather, in addition to more lives lost, the likely result will be heightened tensions with Russia and the very real possibility of another arms race between the countries. That’s why some of those most familiar with this threat are sounding the alarm. According to Jack F. Matlock, the former ambassador to the Soviet Union under Presidents Ronald Reagan and George H.W Bush, the situation already “has begun to resemble a renewal of the Cold War with exchanges of harsh accusations, the application of economic sanctions, and—most dangerous—military muscle-flexing.” Mikhail Gorbachev, the Soviet leader with whom Reagan and Bush worked to build trust and ultimately end the Cold War, is similarly troubled. “I can no longer say that this ‘cold war’ will not lead to a ‘hot war,’” he said. “I fear [the U.S.] could risk it.”

The U.S. interest should be avoiding another arms race with Russia — nuclear or otherwise — and rebuilding the trust that will be necessary to stabilize Ukraine. Further U.S. involvement in the conflict would have the opposite effect, potentially ending the last remnants of cooperation between the countries to contain the spread of nuclear weapons. Moreover, the Obama administration should consider the impact on relations with important European allies, who are pushing hard for a diplomatic resolution, and may even break with Washington policy. Arming Kiev seems to have been a step too far, especially with Ukraine on the point of financial collapse. (It is estimated that in order to survive, Ukraine needs more than $50 billion, which will be largely up to Europe to provide.) The more weapons Washington provides Kiev, the more the price tag will increase.

At nearly every critical juncture over the last year, military escalation has been to the detriment of the Ukrainian people and the government’s own survival. As a result of military action and escalation by both Russia and the West, Ukraine is now on the verge of financial and military collapse — with the currency falling by more than a third this past week and with foreign-exchange reserves down to a few weeks. Kiev knows it can only win by drawing NATO to fight by its side in a long, bloody civil war, bringing us closer to a real East-West crisis.

In every respect, sending more weapons to Ukraine would be recklessly counterproductive. It defies common sense that the United States is considering such a move, especially when the principal victims of continued violence in the region will be innocent civilians in eastern Ukraine. To end this crisis, we need both sides to reject further escalation and embrace the last-ditch peace initiative being pushed by German Chancellor Angela Merkel (with whom President Obama met with at the White House yesterday) and French President Francois Hollande. The sooner the U.S. accepts that a diplomatic resolution is the only option, the sooner we can take a step back from the cliff. The clock is ticking.

Read more from Katrina vanden Heuvel’s archive or follow her on Twitter.