European Council President Donald Tusk has listed the US, under the presidency of Donald Trump, as one of the four main global threats that the EU faces.

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

He listed Russian aggression, China assertion, and radical Islam as threats facing the Union, and added that, "worrying declarations by the new American administration, all make our future highly unpredictable."

Mr Trump has been a vocal supporter of Brexit and said that the EU is, "basically a vehicle for Germany."

"The disintegration of the European Union will 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 US, Russia and China," he added - stating that the only way that European states can be a global force is to stick together.

Mr Tusk said that if the US introduces protectionist economic policies the EU should double its efforts to forge new trade relationships.

"We should use the change in the trade strategy of the US to the EU's advantage by intensifying our talks with interested partners, while defending our interests at the same time," the Polish politician commented.

Yahoo! reports that European diplomats discussed the possibility of the EU formulating a unified response to Trump's ban on individuals from seven prominently Muslim states entering the US. Leaders are reported to have been hesitant to take action given the strength of ties between the US and the EU.