When he returned home, Mr. Trump stoked the fires more, complaining in a tweet that Germany pays “far less than they should on NATO & military. Very bad for U.S. This will change.” His remarks showed no appreciation for how NATO works, how Ms. Merkel is in fact pushing her country to spend more on defense — and, more generally, how comments like this insult a trusted ally.
Europe’s dismay could only have deepened when Congress seemed to cheer Mr. Trump on. Republicans, who once prided themselves as stewards of national security, have shown little concern about the way Mr. Trump treated NATO members or the links between Mr. Trump’s aides and Russia. In a statement, Senator Bob Corker, chairman of the Senate Foreign Relations Committee, gushed over Mr. Trump’s trip to Europe and the Middle East, saying it was “executed to near perfection.”
These new stresses in the alliance come at a bad time. Europe has been battered by the Greek financial crisis; the rise of authoritarianism in Turkey, Hungary and Poland; Britain’s decision to withdraw from the European Union; and the flow of refugees from the Middle East and North Africa.
Meanwhile, Mr. Putin, always eager to expand Russian influence, has exploited every weakness and crisis, along with instigating a few of his own. Russia invaded Ukraine and has interfered in electoral campaigns in the United States, France and Germany. Mr. Putin has meddled in the Baltic States, cultivated far-right-wing allies in Hungary and wooed President Recep Tayyip Erdogan of Turkey on NATO’s eastern flank. He is now courting Italy with a savvy ambassador to Rome and financing for anti-establishment parties.
There are some bright spots. One is that Ms. Merkel seems committed to playing a lead role as the United States pulls back; another is France’s election of President Emmanuel Macron, who has demonstrated a willingness to work in…