MILAN — Now it’s impeachment. To many of the world’s ordinary citizens, not well versed in American constitutional procedures, it means one thing only: Donald Trump, 45th president of the United States, is accused of serious foul play. Pressuring the Ukrainian president to dig up dirt on a political rival’s son? Unbelievable. Is the impeachment investigation, which took shape as October yielded to November, an attempt to “overturn” the 2016 presidential election? The European far right will say that, of course. But most people in Italy — and in Europe — will sit back and watch the show. Without fully understanding it. Nor enjoying it.

A few days earlie r in October came the announcement that the United States would abandon the Kurds, their (and our) allies in the fight against the Islamic State, which has wreaked carnage on London, Berlin, Paris, Nice, Brussels and several other European cities . That the Kurds had sacrificed 11,000 men and women didn’t seem to matter. In his “great and unmatched wisdom”— his own words — Mr. Trump gave Turkey the green light to invade Syria, kick out the Kurds, and create a buffer zone. With Greece and Italy just across the sea, a new stream of refugees can be expected. So far, President Recep Tayyip Erdogan has played the part of a well-paid gatekeeper, but he made it clear he will not tolerate any criticism, let alone a European intervention. Vladimir Putin’s Russia was quick to spot the opportunity: as soon as America retreated, its troops advanced.

All this has left an odd feeling in Italy and southern Europe, that we’ve arrived at a historical watershed and America’s leader has just opened the floodgates to let the water go wherever it wants. The military and geopolitical consequences of America’s actions are important, of course, but there is more. There is a feeling that we — like the Kurds, in a way — must fend for ourselves in what else may come.

This sense of being on our own is a novel one. In the last 75 years, 13 presidents occupied and exited the White House, each with his own plans for Europe. They had hopes, they scored successes, they suffered disappointments. And Europe changed itself significantly after the Second World War — from a bellicose, divided continent to a peaceful community of countries.