President of the European Commission Jean-Claude Juncker arrives for the annual state of the European Union speech in the European Parliament in Strasbourg, France, on Wednesday. (Patrick Seeger/ European Pressphoto Agency)

Peter Wittig is German ambassador to the United States. Previously he served as German ambassador to the United Nations in New York.

The decision by the British people to leave the European Union sent shock waves through Europe. The task of disentangling Great Britain from the set of common rules developed over more than 40 years of British membership in the E.U. is certainly daunting. The referendum has also provoked some serious soul-searching within the E.U. That’s why the leaders of the remaining 27 E.U. member states will meet Friday for a special summit in Bratislava, Slovakia. to discuss how to revitalize the union.

The E.U. is an easy target for criticism — some of it justified, most of it false and populist. The task of unmasking the truth behind populist anti-E.U. rhetoric and stopping the scapegoating of the E.U. for every misery in individual countries is certainly important. The E.U. is a complex animal. It is not a nation-state like the United States, but it is much more than a mere assembly of countries such as the United Nations. Yes, the E.U. needs to focus on the essential tasks it is good at and avoid getting bogged down in regulating the minutiae of the lives of its citizens. Of course, the E.U. must get better at delivering on the expectations of its citizens. But to call into question the entire project of the E.U. is irresponsible populism. This kind of populism, which seems to be a problem in the West, exploits the growing fear of uncertainty in a globalized world.

But don’t write Europe off too soon. The leaders of the E.U. member states know exactly what is at stake. They are up to the task. Perhaps counter-intuitively, cohesion among the E.U. member states has grown even stronger in the wake of the Brexit vote; no single government of a country is seriously contemplating an exit-vote of its own.

The remaining member states know that there are compelling reasons why the union exists. The E.U. is the most successful peace project in European history. It brought prosperity to its members, from Lisbon in the west to Tallinn in the east. Hungary, for example, receives more than $600 per capita annually to invest, as it does, for instance, in new infrastructure. Poland is the biggest beneficiary of E.U. aid, receiving more than $15 billion per year.

The summit in Bratislava will identify common ground among the remaining E.U. member states in order to set a timetable for achieving results on a number of different priorities, including security, fighting terrorism, protecting borders and coping with the refugee crisis. Economics, growth and competitiveness will be on the agenda. Helping young people find jobs should be a special focus. As the biggest country in Europe, Germany accepts its responsibility to forge a consensus among the remaining E.U. member states about how to continue after the Brexit vote. But we cannot do it alone — the European project has always been a team effort of all the member states.

It is only together that the E.U. member states can respond to the challenge posed by a newly assertive Russia. We collectively have a role to play in stabilizing eastern European countries such as Ukraine. We have done this before: Just after the fall of the Berlin Wall, the European Union played a major part in helping the former Warsaw Pact states move toward becoming modern Western democracies.

The refugee crisis is a challenge that no European country can deal with alone — not Greece, where more than 100,000 refugees arrived in the first half of 2016, and not Germany, which took in more than 1.1 million refugees last year alone. But together, the E.U. member states can achieve something, such as the refugee agreement with Turkey which has helped significantly to reduce and control the flow of refugees.

On security issues, the European Union needs the United States — and the United States needs a strong European Union. Europe is the closest partner of the United States, particularly when it comes to the values we share and the threats we face. The United States saved Europe from the horrible war started by the Nazi regime in Germany. Together, we mastered the challenge of the Cold War.  Now, Europe and the United States are fighting global terrorism side by side.

The E.U. summit in Bratislava will be the first crucial step for us to come to terms with the Brexit vote. But beyond that, this is the time for the European Union to prove that it can deliver a safe and secure future for its people. And I am sure the E.U. is up to the task.