Nearly seventy 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 about the threat of imminent global catastrophe—the closer the clock moved to midnight, the closer we were to doomsday. In January, the group of Nobel laureates charged with maintaining the clock changed its time to 11:57, denoting the closest we’ve been to doomsday in more than thirty years. Their reasoning is based not just on the world’s inaction on issues like climate change, but on its provocative march toward a new Cold War.

Indeed, as humanitarian catastrophe engulfs eastern Ukraine, the United States continues to stoke tensions with Russia, most recently by considering providing lethal military aid to the government in Kiev. The move is supported by a bipartisan chorus of think tanks and pundits as well as hawks on Capitol Hill, led by Senator John McCain and including, it appears, President Obama’s soon-to-be defense secretary. At his confirmation hearing in February, nominee Ashton Carter testified that he is “very much inclined” to back the arms transfers, saying, “We need to support the Ukrainians in defending themselves.” (To his credit, Obama himself seems dubious about lethal aid, though he says he’s leaving all options open.)

Arming the Ukrainian military is not in the best interest of either the United States or Ukraine. It will only worsen a bloody crisis that has already killed more than 5,000, with more than 1.5 million refugees and internally displaced persons. There is no military solution to this conflict, only a political one. Supplying US arms to Kiev will only provide ammunition for Russian leaders who believe, fairly or not, that the United States is attempting to turn Ukraine into a Western 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, the net result will not be peace and compromise.” Arms transfers to Kiev are not likely to induce Russian retreat; for both historical and geographical reasons, Ukraine will always be a vital strategic interest for Russia in ways that it cannot be for the United States. Military brinkmanship on Washington’s part is thus doomed to fail; Russia will always hold the stronger military hand on this issue.

The likely result of arming Kiev will be not only more lives lost but the very real possibility of another arms race between the United States and Russia. It could also end the last remnants of cooperation between the two on containing the spread of nuclear weapons. That’s why some of those most familiar with this threat are sounding the alarm. According to Jack Matlock Jr., ambassador to the Soviet Union under Presidents Ronald Reagan and George H.W. Bush, the situation “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 that [Russia and the United States] could risk it.”

Washington needs Moscow’s cooperation on a number of other issues as well, on everything from climate change to counterterrorism to the Syrian civil war and nuclear negotiations with Iran. A renewed Cold War over Ukraine would complicate resolution of these issues. The Obama administration should also consider the impact of its Ukraine policy on relations with important European allies, most of whom are pushing hard for a diplomatic resolution of the conflict, and may even break with Washington over Ukraine.

At nearly every critical juncture over the past year, military escalation, by both Russia and the West, has inflicted immense trauma on the Ukrainian people and threatened its government’s survival. Ukraine is now on the verge of financial and military collapse, with the currency falling by more than a third in just one week and with foreign exchange reserves almost tapped out. (It is estimated that in order to survive, Ukraine needs more than $50 billion, which it will be largely up to Europe to provide.) Kiev knows the only way it can win is by drawing NATO into the fight—with the likely result being a long, bloody civil war.

Our primary national security interest should be rebuilding the trust necessary to stabilize Ukraine. Both sides must reject further escalation and embrace the last-ditch peace initiative pushed by German Chancellor Angela Merkel and French President François Hollande. The broad parameters for a reasonable agreement have not changed in the past year. They include a cease-fire—monitored, ideally, by neutral observers and peacekeepers—an end to arms supplies from all sides and a federal structure that provides more autonomy for Ukraine’s eastern region. Ukraine needs good relations with both Russia and the West; for this to work, NATO expansion must stop, and Ukraine must never join that military organization. The sooner the United States accepts that a diplomatic resolution is the only option, the sooner we can take a step back from the cliff. The clock is ticking.

Watch Next: Stephen F. Cohen on Democracy Now! discussing Ukraine and the new Cold War