This sense of chaos was a lively topic of conversation in Munich, said Sandy Vershbow, a former US ambassador to Russia and deputy secretary general of Nato.
"I'm struck by how many European representatives here have read the collected works of Steve Bannon," he said, referring to Trump's chief strategist, who said before taking office that the Judeo-Christian West is in a global war with Islam.
There was concern, too, among US partners over the slow start to filling posts below Cabinet level in the new Administration.
Given political turmoil on the continent, with populists challenging established parties in the Netherlands, France and Germany in elections this year, how the US's Nato allies in Europe will respond is as unclear as Trump's foreign policy. But there was consensus on what Europe ought to do: Spend more on defence, take care of its own back yard and obsess less about what's happening in the White House.
"Rather than parse every statement from a US official and every tweet from the White House, Europeans need to start thinking about what they have to do for themselves," said Mark Leonard, director of the Brussels-based European Council on Foreign Relations. Europe, he said, has been "infantilised and emasculated" by decades of over-reliance on the US security umbrella.
Chancellor Angela Merkel called for increased military integration between Germany and France. With Britain negotiating to leave the European Union, a major hurdle to long-shelved projects for creating a consolidated military command and even centralised funding will also be removed.
"When you are dealing with a volatile person such as the current Potus, you have to hedge. You have no choice," said Heisbourg. The alternatives, he said, are to build stronger militaries or cosy up to Russia.
Numerous US presidents have pressed other Nato members to spend more on defence in the past, to little effect. But this time may be different, according to some at the conference, both due to the convergence of threats Europe now faces - a revanchist Russia, jihadist terrorists, a refugee crisis and Brexit - and the uncertainty introduced by Trump.