European Council President Donald Tusk | Oliver Hoslet/EPA Donald Tusk slams ‘worrying declarations’ from Trump The EU’s future is already unpredictable and the US administration isn’t helping, says former Polish PM.

European Council President Donald Tusk lumped the "worrying declarations" of U.S. President Donald Trump's new administration together with the geopolitical challenges posed by Russia, China and Islamic terrorism as examples of the threats facing the EU, in a letter to European leaders ahead of their summit in Malta on Friday.

The stark warning, which cited the "worrying declarations by the new American administration," illustrated the extent to which Europe no longer views the transatlantic alliance — a pillar of Western democracy since World War II — as unshakeable, and went as far as to depict the United States as a potential source of anti-European sentiment.

Underscoring the level of anxiety, a senior EU diplomat said lunch at the summit in Valletta will be dedicated to a discussion of the new American administration.

“The decision by Trump on the refugees could have repercussions on the EU,” said the diplomat, adding that refugees could look to Europe if U.S. borders are slammed shut. EU leaders will also discuss related concerns about Russia and the risk that a close alliance between Trump and Vladimir Putin could sideline Europe.

Tusk, a former Polish prime minister, wrote in his letter: "The challenges currently facing the European Union are more dangerous than ever before in the time since the signature of the Treaty of Rome. Today we are dealing with three threats, which have previously not occurred, at least not on such a scale."

"The first threat, an external one, is related to the new geopolitical situation in the world and around Europe," he continued. "An increasingly, let us call it, assertive China, especially on the seas, Russia's aggressive policy towards Ukraine and its neighbors, wars, terror and anarchy in the Middle East and in Africa, with radical Islam playing a major role, as well as worrying declarations by the new American administration all make our future highly unpredictable."

"For the first time in our history, in an increasingly multipolar external world, so many are becoming openly anti-European, or Eurosceptic at best. Particularly the change in Washington puts the European Union in a difficult situation; with the new administration seeming to put into question the last 70 years of American foreign policy."

Tusk went on to warn about the threat posed by "the rise in anti-EU, nationalist, increasingly xenophobic sentiment in the EU itself." At the same time, complacency among "pro-European elite" was resulting in a visible "decline of faith in political integration, submission to populist arguments as well as doubt in the fundamental values of liberal democracy ...," he said.

Tusk sent a similar missive ahead of an EU summit in Bratislava in September, which was later criticized as an overly bleak assessment.

In the new letter, Turks said the disintegration of the EU would "not lead to the restoration of some mythical, full sovereignty of its member states, but to their real and factual dependence on the great superpowers: the United States, Russia and China."

He ended with a call for unity and underlined the importance of transatlantic relations for global order and peace, writing: "We should remind our American friends of their own motto: United we stand, divided we fall."

Jacopo Barigazzi contributed to this story