Leaked letters are said to show the US President's increasing frustration with the North Atlantic Treaty Organisation.
Donald Trump accuses allies in the military alliance of failing to adequately pay for their protection.
The New York Times says Trump wrote to NATO members, including the leaders of Belgium, Canada and Germany.
In his letter to Chancellor Angela Merkel, he warned that what he called Germany's continued underspending on defence undermines the security of the alliance.
Will NATO members heed Trump's call?
And is the North Atlantic alliance still relevant?
(Click here for Android APP of IBTN. You can follow us on facebook and Twitter)
About sharing
Will artificial intelligence replace teachers in classrooms?
May...
"I'm killing those kids, my tax money is doing that" Omar El Akkad on...
Trump showers his Qatari hosts with praise at state dinner
May 1...
Trump visits Qatar as US envoy hints at Gaza progress, quiet diplomacy dominates me...
What can be learned from the latest conflict between India and Pakistan?