The United States gave Germany its democracy and its constitution. It supported German reunification when France and Britain had their doubts. It has some 35,000 troops in Germany, dedicated to the defense of Europe.

But President Trump and his administration now see Europe as an adversary, NATO as a burden and Russia as a friend. Vice President JD Vance and Elon Musk have thrown their support to a far-right party with neo-Nazi members that wants to undermine the German government and supports Russia’s aims in Ukraine.

Germany, perhaps more than any other country in Europe, feels adrift, orphaned and even betrayed by its closest ally. But if Germans have been pushed out of the nest, they are also beginning to respond, amid deep soul searching and questioning about the future — both their own and Europe’s.

The biggest indication that shock is giving way to action came this week, as the lower house of the German Parliament voted to loosen the country’s long aversion to debt so that it could begin rebuilding a military and a domestic infrastructure that had fallen into neglect.

It was a groundbreaking step, given taboos about German militarism. Still, it is one that Germans and other Europeans know they must take to adapt to new hostility coming from both Russia and the United States.

Joschka Fischer, a former foreign minister, radical leftist in his younger days and now a Green party stalwart, said, “I always had a complicated relationship with the United States, which was far from perfect, but the U.S. was always the shining city on the hill.”