German Chancellor Angela Merkel has been relatively neutral in her response to President-elect Donald Trump. (Krisztian Bocsi/Bloomberg News)

Donald Trump split open the U.S. electorate in his runaway bid for the presidency. Now his unexpected ascension is propelling wider fissures in Western unity, as European allies sparred Monday about how closely to work with the future American leader.

The rifts could make it easier for Trump to divide and conquer European leaders to his advantage. But they also put the United States in the unfamiliar position of exploiting European disunity rather than campaigning for a stiff transatlantic response to challenges as varied as Russia, Iran and the global economy.

Most European leaders opposed Trump ahead of his election, worrying that he would upend Western security arrangements that have underpinned European stability for 70 years. But now that he is president-elect, that united opposition is dissipating, as nations make their own, disparate calculations about how to handle his stunning victory.

The approaches to Trump run the gamut: In Britain, leaders appear eager to embrace him in a bid to influence his decision-making. German Chancellor Angela Merkel, meanwhile, has said she looks forward to working with Trump so long as he hews closely to Western values of tolerance. European Commission President Jean-Claude Juncker complained last week that Europe would waste two years waiting for Trump to learn about the world.

These differences are a first sign of how the Western alliance may look under a President Trump: chaotic, unpredictable and more fractured than before. Europe has been struggling to hold itself together after years of economic turmoil, Russia’s 2014 annexation of Crimea and waves of newcomers fleeing war and economic hardship. Britain’s June vote to leave the European Union exacerbated the challenges. But Trump’s victory, in his own words, is “Brexit times five.”

“We should regard it as a moment of opportunity,” British Foreign Secretary Boris Johnson told reporters as he joined a meeting of European foreign ministers on Monday after blowing off a dinner here the previous evening dedicated to crisis talks on the Trump election. (Earlier, Johnson said Europeans should quit their “whinge-o-
rama.”) Trump is a “dealmaker,” he said.

“Change is in the air, and when people demand change, it is the job of politicians to respond,” British Prime Minister Theresa May said in a televised speech Monday, referring to the forces across the West that gave rise to both Brexit and Trump.

But other European leaders are taking different messages from the Trump victory. Many have a difficult path to navigate: Embrace Trump too easily and they risk emboldening their own anti-establishment forces at home. But by rejecting him, they could cut off support from their most powerful ally and look out of touch with their own voters, many of whom are concerned about migration, economic stagnation and the downsides of globalization — the same issues that many say galvanized the Trump voters.

“The whole question is whether they’re going to show unity on all of these matters, or whether they’re going to move on this in a bilateral way, each one going to Washington to try to make the best possible deal with the new American president,” said Pierre Vimont, a former French ­diplomat who is a senior associate at Carnegie Europe, a think tank.

European foreign and defense ministers gathered Monday in Brussels for a long-planned meeting to discuss efforts to improve security and defense cooperation. The session was spurred by Britain’s decision to leave the E.U. and gained new urgency after the U.S. election. 

But many avoided taking a sharp stand on Trump. French leaders said only that they would move forward with their security plans without waiting for the new U.S. administration to develop its policies.

“Europe should not wait for the decisions of others. It must defend its interests, that is to say, the interests of Europe, and at the same time affirm its strategic role in the world,” said French Foreign Minister Jean-Marc Ayrault, who, like his British counterpart, skipped the Sunday emergency dinner. The snub — blamed on a scheduling conflict — was a subtle way to downgrade France’s role in the political crossfire. Leaders of France’s Euroskeptic, anti-immigrant National Front party said over the weekend that Trump representatives had reached out to them to work together. The party is surging at the polls ahead of a presidential election next year.

Other nations appear eager to use any opening by Trump to ease sanctions against Russia. The Obama administration has pushed unity among the 28 E.U. countries on sanctions ever since Russia’s annexation of Crimea, but many E.U. diplomats believe that Europe would quickly dismantle at least some of its sanctions if Trump eased U.S. sanctions first. That would be a slap to East European nations, many of which fear Russian aggression, and to Merkel, who has forced unanimity on sanctions at one fractious summit after another.

Merkel is also Europe’s most robust challenger to Trump’s rise. In the days since his victory, she and her allies increasingly appear to be grappling with the notion that they may be standing alone in defending the post-World War II Western order, as one partner after another has fallen away. 

Germany has traditionally shied away from funding a robust military because of its Nazi past. Now leaders are talking about the need to be more self-sufficient for their own security, fearful of dependence on a United States whose instincts they fear.

“For us, it is clear: Europe needs to take more responsibility for itself,” German Defense Minister Ursula von der Leyen said Monday.

Some European leaders appear ready to dismiss Trump altogether.

“I think that we’ll waste time for two years while Mr. Trump tours a world that he is completely unaware of,” Juncker told students in Luxembourg last week.

The difference between Juncker and the rest of Europe? As the unelected head of the European Union’s vast bureaucratic machine, Juncker faces no voters.