Reuters-- Diplomats have sketched scenarios they fear could plunge transatlantic relations into crisis: a trade war, military conflict over North Korea, or the collapse of a Cold War-era arms treaty. They wonder if their post-war alliance can survive if any of them come true.

Since Trump took office nine months ago, governments in Berlin, Paris and London have wavered between alarm at his rhetoric and a shaky sense that his worst instincts can be contained by the “grown ups” in his cabinet and pressure from allies.

But the Iran decision, taken despite personal appeals from France’s Emmanuel Macron, Germany’s Angela Merkel and Britain’s Theresa May, has changed the calculus in Europe, according to diplomats, politicians and analysts.

No longer is there an underlying confidence that Europe can muddle through three more years of Trump without fear of major, and possibly lasting, disruptions to the relationship. Nor is there faith that Trump, when the stakes are high, will listen to what his advisers and partners tell him.

The anxiety is especially acute in Germany, whose own identity is anchored in its relationship with the United States and whose reliance on Washington, particularly in defense and security matters, runs deeper than that of France or Britain.

“There is a sense of desperation in Berlin, a sense that Trump does not know what is at stake, that he doesn’t understand the historical factors that are at play here,” said Wolfgang Ischinger, a former German ambassador to Washington and chairman of the Munich Security Conference.

“The transatlantic relationship is all about trust. In that sense, the Iran decision takes us to a new level. It is a breach of trust,” he said.