PARIS — Angela Merkel rarely drops thunderbolts, and never by accident.

The cautious, conservative German chancellor, who has governed mostly incrementally for 12 years, has made two such game-changing pronouncements in the last two years. The first time — controversially — she threw Germany's doors open to nearly a million refugees from Syria and elsewhere in 2015.

The second time was on Sunday, when she described the NATO and G7 summits she attended last week with U.S. President Donald Trump and British Prime Minister Theresa May as "unsatisfactory,” adding that Europeans needed to take more responsibility for their security.

"The era in which we could fully rely on others is over to some extent — that’s what I experienced over the past several days,” she said in Munich on Sunday. “We Europeans must really take our fate into our own hands.”

To be sure, the veteran German leader was rallying her Bavarian conservative allies at a campaign event in a beer tent. She has not given up all faith in the United States' commitment to European security. Nor is she yanking up the drawbridge with Britain after the U.K.'s damaging vote to pull out of the European Union or suggesting the EU will have to go it entirely by itself.

Merkel is well aware that Europe has neither the military capability, the intelligence resources nor the political organization — let alone the resolve — to face off alone against Vladimir Putin's Russia.

What she is doing is making it clear, following the election of resolutely pro-European President Emmanuel Macron in France, that the answer to increasing transatlantic and cross-Channel uncertainty should be to strengthen the EU, shore up the eurozone and take the next steps in building a European security and defense union.

The appropriate historical parallel might be with post-war West German Chancellor Konrad Adenauer's reaction to the 1956 Suez crisis, when the U.S. and the Soviet Union forced Britain and France to abandon a joint invasion of Egypt with Israel.

Adenauer was meeting with French Prime Minister Guy Mollet in Paris on the day when Mollet took a phone call from British Prime Minister Anthony Eden, informing him that Britain was pulling out of the Suez operation under U.S. pressure, forcing France to follow suit. "A united Europe will be our revenge," Adenauer told Mollet, who responded by dropping French objections to the establishment of the European common market, the forerunner of the EU.

France and Britain drew opposite lessons from the Suez humiliation, which effectively ended their era as colonial powers. The French concluded that neither the perfidious British nor the overbearing Americans — often lumped together as "les anglo-saxons" — could be trusted. Henceforth France would develop its own nuclear deterrent and pursue an independent European foreign policy. The British concluded they would never be able to act without the United States again, and that they should hug America tight.

Brexit followed by the election of an "America first" president puts international relationships at a less obviously dramatic but equally important turning point. Trump has cast doubt on NATO's mutual defense guarantee and disparaged multilateral trade and climate agreements. Britain has vote to cut itself loose from the main economic and political community in Europe.

Merkel has responded with an act of leadership. Having steadied the European ship after the shock of Brexit, she is telling her fellow Germans that they need to overcome their historically rooted squeamishness about defense and get over their fears that other Europeans are out to take advantage of them.

This positions her to run a resolutely pro-EU election campaign, as Macron did in France. In doing so, she’s robbing the mantle from her strongest opponent — Social Democratic Party leader Martin Schulz, who has the aura of "Mr. Europe" after his time as European Parliament president — and rubbing salt into the SPD's divisions over greater defense spending and a more active military role for Germany.

She is also telling Macron that he will find a willing co-leader in building the EU into a more effective player in international security and diplomacy. And she is charging Trump and May a public political price for their countries' rejection of multilateral governance.

Her message, directed at Trump as much as it was directed at anybody, was a result of her exasperation at his refusal, despite intense pre-summit pleading from European allies, to make an unequivocal commitment to NATO's Article V mutual defense clause — the backbone of the alliance's deterrence for decades.

Instead, Trump publicly lambasted his allies for their weak defense spending, implying that many owed America or NATO billions in past military spending. The nationalist president seems intent on turning NATO's d'Artagnan doctrine — "one for all and all for one" — into a mafia tough’s protection racket: "Nice territory you got there; hate to see anything happen to it.”

Some British commentators have suggested it was unfair of Merkel to lump May in with Trump, since Britain has stood on Germany's side when it comes to NATO, free trade and the Paris climate change agreement. The British prime minister has stressed that the U.K. is not leaving Europe and that it remains committed to cooperation on security and defense and the closest possible relationship with the EU.

To be sure, the next steps in European integration will neither be quick nor easy.

But the U.K.'s looming departure is a severe blow to German interests, and Merkel's message to Britain is that it cannot expect to preserve the trade benefits of EU membership without abiding by the club's rules. It comes as May has been trying to rescue her faltering general election campaign with a fresh round of Europe-bashing, suggesting the other 27 EU members are ganging up to punish Britain.

To be sure, the next steps in European integration will neither be quick nor easy. Berlin and Paris are far from full agreement on how to build a more effective European defense capability, how far and under what circumstances to intervene abroad, and above all how to strengthen the eurozone. And others, such as Poland and Hungary, present an illiberal challenge from within to further EU unity.

But whatever comes next, historians will look back on Merkel's Munich beer tent speech as pivotal — the moment when the leader of Europe's most powerful economy decided the time had come for greater emancipation from the U.S.’s incoherent leadership.

Paul Taylor, contributing editor at POLITICO, writes the Europe At Large column.