Brussels - NATO leaders held emergency talks at their summit after US President Donald Trump demanded allies immediately increase defence spending, throwing the meeting into crisis.
Secretary General Jens Stoltenberg called an extraordinary session of NATO's ruling North Atlantic Council on July 12 after Trump repeated demands for allies to spend more on their militaries, singling out Germany for special criticism.
Diplomatic sources told AFP that Trump used a meeting between the 29 NATO leaders and the presidents of Ukraine and Georgia to repeat for countries to meet a spending target of two percent of GDP immediately, instead of by 2024, and to eventually double spending to four percent.
After an opening day of summit talks marked by clashes between Trump and German Chancellor Angela Merkel, NATO leaders had hoped to focus on policy on Ukraine and Afghanistan.
But just days out from a high-stakes meeting with Russian President Vladimir Putin, the mercurial US leader threw the transatlantic alliance into disarray.
"Trump took advantage of his speaking time to return to the issue of burden sharing" during the Ukraine and Georgia meeting, a diplomatic source told AFP, prompting Stoltenberg to call the special talks.
"Trump pointed to several countries, especially Germany," the source said, adding that the US president used "hard language, with repeated references to Germany" and even to the German chancellor, "calling her Angela".
Another diplomatic source confirmed that a "special session on burden sharing is ongoing."
The sources refused to comments on reports that Trump threatened to pull the US out of NATO if his demands were not met.
The drama came after Trump renewed his criticism of European allies on Twitter, repeating the demand he made Wednesday for NATO members to double their defence spending target.
Trump complained that Germany and other NATO allies "pay only a fraction" of the cost of defending Europe, leaving the US to pick up the tab.
"Germany just started paying Russia, the country they want protection from, Billions of Dollars for their Energy needs coming out of a new pipeline from Russia. Not acceptable! All NATO Nations must meet their 2% commitment, and that must ultimately go to 4%!" Trump tweeted.
Apart from the US, only three NATO countries hit the two-percent target in 2017 -- Britain, Greece and Estonia -- but four more are expected to clear the threshold this year.
Trump, who has said his meeting with Russian President Vladimir Putin next week "may be the easiest" part of his European tour, kicked off the summit with a blistering attack on Germany, calling it a "captive" of Moscow because of its gas links.
- Afghanistan, Ukraine talks -
Trump's demand on Wednesday to double the defence spending target rattled allies, with Bulgarian President Rumen Radev saying that "NATO is not a stock exchange where you can buy security".
NATO Secretary General Jens Stoltenberg said on Wednesday that he would "focus on what we have agreed" on meeting the two-percent target, rather than addressing Trump's four percent demand.
Thursday's talks will focus on Ukraine and Afghanistan, where NATO maintains a training and support mission to help local forces fight the resurgent Taliban.
Trump has explicitly linked NATO with a transatlantic trade row by saying the EU shut out US business while expecting America to defend it, singling out Germany for particular criticism.
Europe's biggest economy spends just 1.24 percent of its GDP on defence, compared with 3.5 percent for the US.
- Trump heading to Britain -
Trump has taken particular exception to the proposed Nord Stream II gas pipeline, which is set to run from Russia to Germany under the Baltic Sea.
Merkel, who grew up in communist East Germany, shot back that she knew what it meant to be under Kremlin domination and was glad a united Germany was now able to "make our own independent policies and make our own independent decisions".
European diplomats had feared a repeat of last month's divisive G7 in Canada, when Trump clashed with his Western allies before meeting Kim Jong Un at a summit, where he praised the North Korean leader as "very talented".
Trump will meet Putin in Helsinki on July 16 for their first summit amid an ongoing US investigation into possible Trump campaign collusion with Russia.
There have been fears that Trump, keen to be seen to make a breakthrough with the Kremlin strongman, might make concessions that would weaken Western unity over issues like Ukraine and Syria.
Trump heads to Britain on Thursday, where the government is in crisis over Brexit and where tensions with Russia have spiked after London blamed Moscow for the death this month of a British woman from contact with the Novichok nerve agent.
By Damon Wake