U.S. President Donald Trump (R) shakes hands with Federica Mogherini, the EU's High Representative for Foreign Affairs and Security Policy, during the EU-USA Leaders' Meeting at the European Council headquarters, in Brussels, Belgium, May 25, 2017. [Photo/Xinhua]

BRUSSELS -- European Council President Donald Tusk admitted on Thursday that the bloc is still at odds with the United States over issues like climate, trade and Russia.

"My feeling is that we agreed on many areas. First and foremost, on counterterrorism... But some issues remain open, like climate and trade," Tusk told reports after meeting with visiting US President Donald Trump.

"And I am not 100 percent sure that we can say today -- we meaning Mr. President Trump and myself -- that we have a common opinion about Russia, although when it comes to the conflict in Ukraine, it seems that we were on the same line," he added.

Tusk said he told the billionaire US president that they should consolidate "the whole free world around those values, and not just interests."

"Values and principles first - this is what we, Europe and America, should be saying," said Tusk.

Trump, on his first overseas trip as US president, on Thursday met with Tusk and Jean-Claude Juncker, the president of the European Commission, both of whom have been critical of Trump's remarks in the past.

Later on Thursday, Trump and leaders of other NATO countries will meet for the first time to map out the future of the organization, and try to narrow their differences on its budget.

The US President has had a fractious relationship with Europe since his candidacy, in which he publicly applauded the pro-Brexit campaign before and after the referendum which saw Britain decide to leave the European Union.

In January, as president-elect, he rattled many European allies by stating in an interview that NATO (North Atlantic Trade Alliance) was obsolete, and indirectly threatening allies to leave the pact if they did not boost defense spending.

Donald Trump's first trip abroad as president has already taken him to Saudi Arabia, Israel, the West Bank of the Palestinian territories, the Vatican before arriving in Brussels. His final leg of the journey will be in Sicily, Italy, where he will join a G7 summit in Taormina.