Amid the pressure from Trump over defense budgets, the European Union is drafting plans to spend more of its common budget on defense research, pool procurement and give the arms industry better access to finance.
After meeting with Trump on Thursday at the EU, European Council president Donald Tusk said he and the US precedent agreed on the need to combat terrorism but some differences loomed large.
"I'm not 100% sure that we can say today, we meaning Mr President Trump and myself, that we have a common opinion about Russian Federation".
"However, my 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", Tusk said.
Belgium's premier Charles Michel said it was time to "defend the values of the free world" while German Chancellor Angela Merkel said North Atlantic Treaty Organisation was central to the West's security. "This is what we, Europe and America, should be saying", Tusk added, echoing - whether intentionally or not - Trump's campaign motto "America first". A special prosecutor was appointed to investigate earlier this month.
Ahead of a working lunch with Macron, Trump said terrorism was at the top of the agenda, while also offering his congratulations to the 39-year-old for his "tremendous victory".
Tusk told reporters, "I'm sure that I don't have to explain why" the European Union leaders agreed "first and foremost" on counterterrorism issues with Trump.More news: Protests Target Both NATO and Trump in Brussels
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Meanwhile, the EU and the U.S. agreed to start work on a plan to increase trade cooperation, a European Commission spokeswoman said.
Brussels, which was targeted in a 2016 terror attack that left 32 dead, is the penultimate stop for Trump on a four-country tour that marks his first overseas trip as USA president and that has coincided with a growing political storm at home over possible Russian interference in the 2016 election.
He will also speak at NATO's gleaming new $1.2 billion new headquarters.
"At that time the questions were on Brexit", and on the survival of the EU, a senior European official said on condition of anonymity.
Federica Mogherini, the EU foreign policy chief, and European Parliament President Antonio Tajani joined part of this morning's talks. However, EU officials believe he has come to a greater appreciation since taking office of the value of European integration to United States interests.
As they sat for the talks, Juncker and Tusk tried to make light of the EU's complicated institutional structure to a USA president that has been highly critical of the bloc.