He came, he saw, he vandalized.

Donald Trump’s rampage of political destruction through Brussels and Britain has left NATO allies, European Union partners and believers in a U.S.-U.K. “special relationship” shaking their heads in dismay.

And that’s before Monday’s one-on-one with Russian President Vladimir Putin, which could illustrate yet again that this U.S. president is more comfortable dealing with nuclear-armed autocrats than with the elected leaders of liberal democracies that have been America’s closest friends since 1945.

Whatever the outcome of the unpredictable summit in Helsinki, it’s up to the European Union now to clear up the wreckage from Trump’s display of bullying, boorishness and boredom, and take on leadership of a rules-based international order with like-minded partners.

To quote a phrase that earned infamy when the EU failed to stop the Balkan wars of the early 1990s, this really should be the “hour of Europe."

Trump repeatedly attacked the EU and chose to lionize those who are in conflict with it over liberal value.

On a range of issues from trade to climate change to bolstering the United Nations, the EU has more in common with Canada, Japan, Australia, New Zealand and South Korea, and the big emerging markets of China, India, Brazil, Turkey and Mexico, than it has with this U.S. administration.

European leaders can no longer hide behind the wishful thinking that the United States will soon revert to normal. The leader of the free world doesn’t want to be encumbered with allies or tied down by trade rules or diplomatic niceties.

His veiled threat to go it alone without NATO if Europeans don’t immediately raise their military spending by massive amounts should be taken seriously. Europe can no longer afford the luxury of assuming the U.S. will always be there with its protective umbrella.

Trump could be in power for another six years. The Europe-friendly old guard in the State and Defense Departments, Congress, business and the U.S. strategic community appear powerless to stop or even restrain him. And he’s out to destroy key allied leaders politically.

Trump behaved on this trip as if he were determined to force regime change in Berlin and London rather than Pyongyang or Moscow.

He tried to destabilize Chancellor Angela Merkel, weakened by coalition in-fighting, by attacking Germany over its gas contracts with Russia, its deficient defense spending and its immigration policy. He ambushed Prime Minister Theresa May at her moment of maximum vulnerability by saying Britain is wrong to pursue the soft Brexit she is proposing and praising Boris Johnson, who resigned as foreign secretary in protest after failing to persuade the Cabinet to make a clean break with Europe.

While in Brussels, Trump repeatedly attacked the EU and chose to lionize those who are in conflict with it over liberal values: Polish President Andrzej Duda and Turkish President Recep Tayyip Erdoğan.

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So what should Europe do? Show that multilateral life goes on without America if necessary.

First, trade. The EU should build a web of free-trade agreements with like-minded nations and regional groupings, while working with China to open up investment and curb intellectual property theft through negotiation rather than punitive tariffs.

The bloc should also use trade, aid and institution-building tools more effectively in its own neighborhood, starting with the Balkans, where the goal of EU membership gives Brussels most influence.

Climate change is another opportunity for leadership. The EU must ensure it meets its own targets for reducing carbon emissions under the Paris accord and must set itself ambitious new ones, including for financing climate adaptation in developing countries.

It should also continue to leverage its rule-setting power over data protection, privacy and technical norms to build international standards, as it has done boldly with the General Data Protection Regulation.

Finally, the EU must invest seriously in common defense. European nations can help NATO demonstrate the kind of unity, resolve and deterrence that Trump’s behavior has shaken by getting more serious about boosting their common defenses and industrial cooperation.

It should also use new EU tools to promote military research and developing joint arms procurement, and get behind a French-led initiative to work on a common strategic doctrine for crisis management and humanitarian intervention.

Britain must be included as a military partner and a useful part of Europe’s defense, industrial and technological base rather than shutting it out as a punishment for Brexit.

The biggest obstacle to assuming more responsibility for the multilateral system is the EU’s own debilitating internal divisions.

The EU cannot solve the conflicts in the Middle East or keep a lid on nuclear proliferation without Washington. But it can limit the damage of U.S. neglect or recklessness, as French President Emmanuel Macron did by brokering a solution to the crisis between Saudi Arabia and Lebanese Prime Minister Saad Hariri, or as Germany has been doing quietly by helping ease the conflict between Riyadh and Qatar.

It can also keep channels of dialogue and cooperation open with Iran — despite Trump’s unilateral withdrawal from the international agreement to curb Tehran’s nuclear program and U.S. threats to kneecap European firms that do business with the Iranians.

Overall, Europe can make multilateralism work better where its tools are strongest — but it is not yet living up to its own ambitions.

The biggest obstacle to assuming more responsibility for the multilateral system is the EU’s own debilitating internal divisions. Beggar-thy-neighbor squabbles over cross-border migrant flows, east-west differences over the rule of law and an open society, efforts by northern countries to rein in Franco-German leadership, and perennial interinstitutional squabbles in Brussels all sap Europe’s international ambitions.

Of course, many will continue to hope that a post-American Europe is not about to dawn. They will point to increased U.S. investment on the European Deterrence Initiative and a beefed-up military presence in Central and Eastern Europe.

But Europe would be wise to plan on doing more for itself and with like-minded partners in case the darkness in Washington gets worse and lasts longer than we all hope.

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