The only person happier than Boris Johnson over Britain’s exit from the European Union may be Vladimir Putin.

The Kremlin has spent years trying to create fissures within the NATO alliance and the European Union, but with little success. Now Britain’s vote to leave the EU fulfills Putin’s wish for a more divided Europe, one potentially preoccupied with its own disagreements while London’s influence recedes.

“They are drinking copious amounts of vodka in the Kremlin today,” Derek Chollet, a former senior advisor at the U.S. Defense Department, told Foreign Policy.

“What makes it depressing is that this was an unforced error,” said Chollet, now at the German Marshall Fund of the United States. “Putin has been trying to force divisions in the West, but he actually hasn’t been succeeding that well. This is a benefit to him without him having to do anything.”

Russian politicians celebrated the vote, hoping it would sabotage the continent’s resolve when it comes to enforcing the sanctions levied against Russia over its military intervention in Ukraine.

“Without Britain, there won’t be anybody in the EU to defend sanctions against us so zealously,” Sergey Sobyanin, the mayor of Moscow, wrote on Twitter.

Andrei Klimov, deputy chairman of the international affairs committee of the upper house of the Russian Parliament, told the New York Times on Friday that he doesn’t “think the European Union will now have time to think about Ukraine or about sanctions.”

Michael McFaul, a former U.S. ambassador to Russia, agreed. He tweeted Friday that “Putin benefits from a weaker Europe. UK vote makes EU weaker. It’s just that simple.”

The advocates of Britain’s departure from the EU argued that the country would be able to reassert itself on the world stage without being weighed down by the European Union’s bureaucracy or the need to send large amounts of money to Brussels each year.

But former senior U.S. officials and analysts say Britain will be weaker and more isolated as a result of the move.

The vote came just two weeks before a major NATO summit kicks off in Warsaw, Poland, that is supposed to refocus the alliance’s attention on the growing threat posed by Russia. But Britain’s departure from the European Union — and the specter of fraying unity across the continent — will hang over the meeting, and NATO leaders are already trying to steady nerves within the alliance over Thursday’s referendum.

NATO Secretary-General Jens Stoltenberg issued a statement Friday insisting that the vote would not alter Britain’s status in the alliance. As London “defines the next chapter in its relationship with the EU, I know that the United Kingdom’s position in NATO will remain unchanged,” Stoltenberg said.

Britain’s importance as a strategic ally for the United States, as a power that could “punch above its weight,” is partly based on its ability to exert influence over Europe’s approach to national security and persuade other EU members to back Washington’s tougher line from the war in Afghanistan to challenging Russia. That status will be undercut by the British electorate’s decision to bail out of the EU, experts said.

The vote also could have a potentially significant knock-on effect, possibly stripping Britain of its nuclear arsenal and changing the strategic nuclear landscape of Europe.

A clear majority of voters in Scotland opposed leaving the EU, and Scottish leaders say they will hold a new referendum on whether Scotland should secede from the United Kingdom. If Scotland bolts, however, Britain would be forced to confront another problem with serious implications for European security: It would have no place to dock its nuclear-armed submarines.

Since the 1960s, the Royal Navy has parked its four Vanguard nuclear-armed submarines at Faslane in Scotland. There is no other facility in the United Kingdom capable of housing the vessels, so Scottish independence would force a stark choice: Lose the capability altogether, or spend at least a decade — and millions of pounds — building new port facilities for the vessels. If Britain were to lose its undersea atomic arsenal, the United States could be forced to rewrite its own nuclear strategy.

London’s ambitious plans to expand its military spending over the next decade after years of deep cuts could be another casualty of the Brexit. If outside forecasts prove correct, Britain’s economy could shrink by up to 6 percent, draining away funds that could have otherwise been devoted to the defense budget, which has fallen significantly in recent years. Military spending declined 8 percent between 2010 and 2015, with 31,000 service members cut from the force amid major spending cutbacks across the government.

“The U.K. has been one of this country’s most important partners. It will be less willing and able to play that role,” former U.S. diplomat Richard Haass, president of the Council on Foreign Relations, told reporters during a teleconference. “The net result is the special relationship will be that much less special.”

Even before the referendum, Britain’s status as a staunch and crucial military ally of Washington had faded in recent years. London pulled its combat troops out of Afghanistan in 2014, and the British Parliament rejected possible U.S.-led military strikes against the Syrian regime in August 2013.

Those changes were happening just as France — which for decades had been regarded as a high-maintenance partner for Washington — has taken on a more muscular role, showing a greater willingness to deploy its troops alongside American forces or to launch its own counterterrorism missions in Africa’s Sahel region.

“When it comes to working on urgent policy crises, France has become the more activist, more engaged partner,” Chollet said.

But London hasn’t completely pulled back. British warplanes fly daily missions over Iraq, and the government has committed to supply one of four NATO battalions to be stationed in the Baltics next year. Analysts expect Britain to honor those commitments, but questions remain over what kind of foreign deployments a potentially more inward-looking British government may undertake in the future.

British and EU leaders now face the daunting task of hammering out the details of London’s disentanglement, a time-consuming job that will probably crowd out other priorities, experts said.

Field Marshal Lord Bramall, a former head of the British Army, issued an appeal before the Brexit vote to stay in the EU, saying London’s voice was needed to ensure a stable balance of power in the West. He argued that “a broken and demoralized Europe just across the Channel, lacking the practical influence of this country, would constitute a far greater threat to our future, indeed to the whole balance of power and equilibrium of the Western world, than having to continue to endure some irritating and unnecessary meddling from Brussels.”

Britain’s absence will be felt acutely in the European Union’s burgeoning military force, designed to fill gaps in missions in areas of Africa and Eastern Europe where an overstretched NATO doesn’t have a presence. While the U.K. plays only a small role in the program, planning in Brussels has “always been based on the idea that Britain would become an important contributor,” said Christopher Chivvis, the associate director of the International Security and Defense Policy Center at Rand Corp.

Without the U.K.’s backing, the project “is for all intents and purposes no longer possible.”