Dr. Strangelove would have felt at home at the Nuclear Security Summit in The Hague on Monday and Tuesday. For starters, the chamber where 53 countries came together around a great circular table bore an uncanny resemblance to the War Room in Stanley Kubrick’s classic 1964 satire about atomic Armageddon. And, like the characters in Dr. Strangelove, many of the world leaders in the Dutch capital seemed reluctant to believe the disaster playing out in front of their eyes.

As it happens, these biennial summits, first organized by President Barack Obama in 2010, were intended originally to address the risk of atomic weapons falling into the hands of terrorists, not the beginning of a new standoff between the world’s greatest nuclear powers. But that is exactly what is taking shape.

Obama, German Chancellor Angela Merkel, British Prime Minister David Cameron, U.N. Secretary General Ban Ki-moon and other leaders in The Hague tried hard to grapple with the fact that Russian President Vladimir Putin is on the warpath, and Russia, lest anyone forget, is the second greatest nuclear power in the world.

Yet the most obvious measure taken against Putin, telegraphed long in advance, was to blackball Russia from the G8 group of most industrialized democracies. The G7, as it’s being called once again, will not meet in Sochi this summer as planned, but in Brussels. And so on.

Russian Foreign Minister Sergey Lavrov, standing in for Putin at The Hague, literally shrugged. The G8 “is an informal club, with no membership cards,” he said. “No one can expel anyone from that club by definition.”

Lavrov said the G8 has been superseded by the G20, a bigger club. Then, just to underscore how important Russia remains on the diplomatic front, Lavrov said that to the extent the G8 served any purpose, it “maintained its raison d’être primarily as a forum for dialogue between the leading Western nations and Russia, where we would discuss issues such as Iran’s nuclear program, the nuclear status of the Korean Peninsula, the crisis in Syria, the situation in the Balkans, and a few other things.” But there are plenty of talking shops around for those issues, Lavrov suggested. “So, if our Western partners believe the G8 has become irrelevant, so be it. For our part, we do not cling to this format, and we wouldn’t see it as a tragedy if it were to cease to exist.”

The seven remaining members of the “club” said in a statement Monday night that “Russia’s action will have significant consequences,” and in a final press conference, Obama tried to dis Putin right where it hurts: “"Russia is a regional power that is threatening some of its immediate neighbors not out of strength, but out of weakness,” said Obama. “The fact that Russia felt it had to go in militarily and lay bare these violations of international law indicates less influence, not more.”

But all this still leaves open the question of what the West is going to do about it. To be sure, visa restrictions and asset freezes have been announced targeting Putin cronies. But it’s clear that serious sanctions against major sectors of the Russian economy are going to be hard to organize and harder still to implement.

Britain does not want to see the City of London hemorrhage hundreds of billions of pounds if Russian investors pull out. The French do not want to stop the sale of warships worth $1.66 billion. The Germans don’t want to jeopardize their access to Russian oil and natural gas, which supplies about a third of their energy needs. If Putin grows still more aggressive, the Europeans might suck it up and impose really tough sanctions, but they will be slow taking effect. And one thing we’ve learned about Putin in the last month is that he moves fast.

In a matter of weeks, Putin has sawed the Crimea off Ukraine and glued it into the Russian Federation. He has intimidated and humiliated the fledgling pro-European government in Kiev. He has left open the possibility that his troops will roll across the frontier. He has kept the world guessing about his plans to rebuild the Russian empire (which covers a pretty big “region””). And nothing Washington, Brussels or NATO has said or done seems like much of a deterrent.

In Ukraine, you can almost smell the threat of war like the electricity-charged air before a summer storm. On the eve of the summit in The Hague, a U.S. congressional delegation in Kiev emerged from meetings with Ukraine’s prime minister and defense chiefs grim and sobered by what they’d heard.

Republican Sen. Kelly Ayotte of New Hampshire said officials are still alarmed and worrying, despite vague assurances to the contrary from Moscow, that Putin may decide to grab more Ukrainian territory. Russian intelligence activity on the Ukrainian side of the frontier has added to that concern. Three suspected Russian agents were seized at the weekend by Ukrainian authorities.

Democratic Rep. Stephen Lynch of Massachusetts told The Daily Beast that Russian forces are not only built up on the Russian side of the border but are in a highly aggressive deployment far beyond anything required for mere military exercises. “They are massed in a very small area. They are stacked in a threatening posture,” said Lynch, “and if you ask me if they are coming across or not, all I can say is I hope not but I don’t know.”

The three-strong congressional delegation called for military aid—from small arms to technical assistance and communications equipment—to help Ukrainian forces prepare themselves as best they can for any action. As Ayotte noted, ousted Ukraine President Viktor Yanukovych had “gutted the Ukrainian military.”

The American lawmakers argued there is little time to waste in stiffening Western actions, from earmarking Russia’s financial sector for American and European sanctions to boosting NATO’s presence in the countries neighboring Ukraine, from Poland to the Baltic States.

Lynch also pointed out one of the bitter ironies on the nuclear front. In 1994 all five permanent members of the U.N. Security Council, including the U.S. and Russia, signed onto a document known as the Budapest Agreement guaranteeing Ukraine’s sovereignty and its borders. In exchange, Ukraine gave up hundreds of nuclear warheads, only to discover now that it’s virtually defenseless against its faithless neighbor.

“Think about the message this is sending to every other nation who we are asking to relinquish nuclear weapons or the capacity to develop nuclear weapons,” said Lynch. (Iran would be one that comes to mind.) If the West fails to defend Ukraine, he said, “the message here is … that they should hang on to their nuclear weapons.”

The Central European members of NATO, meanwhile, are stepping up their own defense plans and their military spending. Poland is accelerating deals on missile defense systems and combat and reconnaissance drones worth $980 million. Estonia’s defense ministry says security is now the little Baltic state’s top priority. Poland, Lithuania and Ukraine have revived a plan to form a joint battle group. Britain, meanwhile, has deployed an E-3D early warning aircraft over Poland and Romania to monitor Ukraine. France has offered to dispatch four jet fighters to Ukraine and help it with cyber security.

Whether any of this will impress Putin is another matter. During the Cold War, deterrence was based partly on the doctrine of Mutual Assured Destruction (MAD)—the idea that if either side started using nuclear weapons, both sides would be utterly obliterated in a nuclear holocaust. That was the insanity, precisely, that “Strangelove” parodied, and nobody wants that world to come back.

But deterrence of some sort is still needed in dealing with Russia, and the West has yet to discover what that might be.

With Nadette De Visser in The Hague