Comment: Ukraine peace talks hinge on U.S. security guarantee

By Andreas Kluth / Bloomberg Opinion

Don’t be distracted by whatever “minerals deal” the U.S. and Ukraine may or may not hash out in the coming weeks, for it will not address the main obstacle to the kind of cease-fire between Russia and Ukraine that President Trump so badly wants to broker.

That question is: How can third-party guarantors credibly assure the security of Ukraine after an armistice?

Credibility: Every devil in every detail is wrapped up in that one word. The concept is so slippery that it’s kept strategists busy at least since the American scholar Thomas Schelling (who later won a Nobel Prize for his work in game theory) analyzed types of deterrence during the early Cold War. We can’t ask Schelling to weigh in on Ukraine today (he died in 2016). But here’s what he wrote about American troops — and obliquely about their British and French partners as well — stationed in West Berlin at the time.

“What can 7,000 American troops do, or 12,000 Allied troops?,” he asked. “Bluntly, they can die. They can die heroically, dramatically, and in a manner that guarantees that the action cannot stop there. They represent the pride, the honor, and the reputation of the United States government and its armed forces; and they can apparently hold the entire Red Army at bay.”

What Schelling was describing is a tripwire force. A literal tripwire is a thread that, when a trespasser stumbles over it, triggers an alarm or a detonation or some other consequence that the intruder has reason to fear. A metaphorical tripwire is a relatively modest deployment of troops that could never stop an invading army but that would, if eliminated by the enemy, compel the home nation to seek revenge and enter the war.

Deterrence is said to be strong when two conditions are met: First, the country (or coalition) that sent the tripwire force must seem committed to avenging its troops if they are harmed. Second, the country must also be capable of defeating the aggressor, which in the Ukrainian scenario is Russia under its president, Vladimir Putin.

The Allied tripwire forces in West Berlin and West Germany were an example of successful deterrence: the Cold War, despite several hair-raising crises, never turned hot. Beyond that case, though, precedents of credible tripwire strategies are rare, as Dan Reiter at Emory University and Paul Poast at the University of Chicago have shown.

In 1949, for example, the Americans kept enough forces in East Asia to deter a North Korean attack on South Korea, but by 1950 the American presence shrank, the tripwire lost credibility, and the North went to war. The U.S. posture in the South since 1953 has been more credible again, but that’s no guarantee that it will remain so. In other places — such as Beirut in 1983 and Mogadishu in 1993 — American peacekeepers did come under attack, but the U.S., instead of intervening with overwhelming force, eventually withdrew.

When the U.S. provides the peacekeepers, the question at least isn’t about theoretical capability; the American military could win any single fight it chooses. Not so when others send the troops. In 1995 Dutch soldiers, deployed under the aegis of the United Nations, could not prevent Bosnian Serbs from massacring Muslims in Srebrenica, and there’s little that the Netherlands could have done in the aftermath.

In today’s Ukrainian context, too, it is moot whether, say, a Franco-British tripwire force without American backing would be either capable or credible in deterring Putin from invading again. Trump’s vice president, J.D. Vance, clumsily betrayed his own verdict on the matter when he mocked the idea of guarantees backed by “20,000 troops from some random country that hasn’t fought a war in 30 or 40 years.”

(Vance’s comment was offensive in another way too: Several of America’s European allies have indeed fought in recent decades, in their support of the U.S. in Afghanistan and other places.)

Now consider why Ukrainian President Volodymyr Zelensky is so disheartened by everything Trump and Vance have said and done for the past month, during which they’ve taken up the Kremlin’s absurd narrative that Ukraine (rather than Russia) is the aggressor and Zelensky (rather than Putin) the dictator. During the disastrous bust-up between Zelensky, Trump and Vance in the Oval Office, the point the Ukrainian was trying (and failing) to make was precisely this need for security guarantees to be credible, meaning American-backed.

The Ukrainians have a particular history of trauma. In 1994, they gave up their Soviet-era nuclear weapons in exchange for security guarantees (without tripwire forces to enforce them) from the U.S., the United Kingdom and Russia. Those were worthless, obviously. Following Putin’s annexation of Crimea and infiltration of Donbas in 2014, the Ukrainians were given new guarantees in two other agreements, called Minsk I and II and brokered by Germany and France. Those now look cynically vacuous.

The security guarantee that Zelensky understandably wants, and Putin fears, is Ukraine’s accession to NATO. Inexplicably for somebody who fancies himself a dealmaker, Trump has already taken that chip off the table before negotiations have even begun. The next-best option is American boots on the ground. Trump has ruled that out too.

So the European NATO allies and other Western countries are now discussing laying a tripwire without American support. But that runs into the vexed twin question of capability and credibility;the implied consequence, after all, is a readiness to go to war against Russia.

No matter what else Trump and others propose, there is no skirting the dilemma: Earnest cease-fire talks cannot begin without the prospect of credible security guarantees; no guarantee can be credible without the United States; but the U.S. under Trump is moving away from such a commitment.

During the Cold War, American presidents of both parties saw the stakes in hotspots such as West Berlin as nothing less than what Schelling called “the pride, the honor, and the reputation of the United States.” Trump and Vance are quite clear that they define the stakes in Ukraine, which is fighting for its survival as a nation, as little more than the rare earths in its ground. “I’m not worried about security,” Trump snarled at Zelensky in the Oval Office. “I’m worried about getting the deal done.” The more Trump says that, the less Zelensyy can trust, and thus enter, talks to end the war.

Andreas Kluth is a Bloomberg Opinion columnist covering U.S. diplomacy, national security and geopolitics. Previously, he was editor-in-chief of Handelsblatt Global and a writer for the Economist. ©2025 Bloomberg L.P., bloomberg.com/opinion. Distributed by Tribune Content Agency, LLC.