President Trump is meeting European leaders in Brussels as his international trip continues
European Council President Donald Tusk says he is not sure he shares "a common opinion about Russia" with Donald Trump.
US President Trump has been meeting with a number of EU and European leaders in Brussels.
In remarks after meeting with President Trump, Mr Tusk said: "My feeling is that we agreed on many areas. First and foremost, on counter-terrorism, and I am sure that I do not have to explain why.
"But some issues remain open, like climate and trade. And I am not 100% 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: "My main message to President Trump was that what gives our cooperation and friendship its deepest meaning are fundamental Western values, like freedom, human rights and respect for human dignity.
"The greatest task today is the consolidation of the whole free world around those values, and not just interests."
President Trump also met with the newly-inaugurated French President Emmanuel Macron.
The US leader congratulated Macron on his "tremendous victory" in the recent election.
British Prime Minister Theresa May is also due to meet President Trump at the NATO summit in Brussels.
Mrs May is expected to raise the issue of US leaks in relation to crucial intelligence about the Manchester bombing when she meets the US leader.
Tomorrow, President Trump will travel to Sicily for the final leg of his first foreign trip and a meeting of the G7 leaders.
The trip has also included stops in Saudi Arabia, Israel and Rome.