He wrote the leaders of Denmark, Norway, Canada and Germany last month to ratchet up the pressure, saying "the United States is increasingly unwilling to ignore the European failure to meet shared security commitments". Such an approach could allow joint training, but end the practice of having over-burdened USA taxpayers foot the bill for wealthy Europeans' security.
Some worry an unpredictable Trump, at the U.S. -Russia summit, could agree to take the first steps to embolden Russia, such as halting military exercises or agreeing that Crimea, a region of Ukraine annexed by Russia in 2014, belongs to Russia.
Jon Huntsman Jr., U.S. ambassador to Russian Federation, said U.S. officials have repeatedly confronted Russian Federation about election hacking and said Trump wants to improve relations, but won't let Putin off the hook. One official who asked to speak on the condition of anonymity said "we're entering with our eyes wide open" but "the ball really is in Russia's court" when it comes to changing their behavior.
Administration officials have also said that subjects discussed with Putin would include Syria, where the administration is looking for a political settlement that would allow the withdrawal of US troops there. Still, any move to permanently withdraw American troops from Europe would ultimately require congressional authorization. Trump also rejected the joint communique signed by leaders at the conclusion of the meeting, launching personal attacks against Canadian Prime Minister Justin Trudeau in the process.
The summit will follow a NATO meeting in Brussels where Russian Federation will also top the agenda, said U.S. Ambassador to NATO Kay Bailey Hutchison. "It would weaken the alliance and provide new opportunities for countries like Russian Federation to take advantage of that".
The measures target the financial, energy and defense sectors, and the area of dual-use goods, the European Union said in a press release. So it's understandable for the U.S. to air frustration and ask European nations to do more - especially as some states are yet to meet their standard 2 per cent obligation. They are strategically located to help in other regions of the world, such as counter Iran or strike the ISIS.
Other than with NATO Secretary General Jens Stoltenberg, Trump has no other bilateral meetings now scheduled. All are former Soviet client states: Estonia, Latvia, Lithuania, Poland and Romania. The U.S. spends about 3.5 per cent. That's in direct contradiction of NATO's pledge that an attack against one member is considered an attack against all of them. The U.S. and other large North Atlantic Treaty Organisation allies have also formed a rapid response force, which would ideally be capable of arriving in an area of an incursion quickly.
"We will talk about the biggest increase in defence spending by our allies since the Cold War", she said.
The White House declined to say if and how Trump might punish the countries.
"My guess is that that will be part of the discussion as well, but I don't want to get ahead of the possible summit conversations", Huntsman said.
Last week it emerged that Mr Trump was already considering transferring or withdrawing personnel from Germany, where the United States now has around 35,000 troops.