Then, in a head-snapping pivot at the end, on Thursday he declared the alliance a "fine-tuned machine" that had acceded to his demands to speed up increases in military spending. Must pay 2 per cent of GDP IMMEDIATELY, not by 2025.
"Hes voiced his frustration about the lack of progress many, many times, basically asking 'What have we got for all that money?'" Michael Kugelman, a South Asia specialist at the Woodrow Wilson Center, said that if there had meaningful progress in Afghanistan, a review would be unlikely.
Islamabad, however, denies the charge, with several Pakistani officials as well the Army irked at the Trump administration's request to "do more".
He said it was "a little tough for a little while" and that he had told the Europeans he would be "very unhappy" if they did not up their spending "substantially".
Trump emerged declaring his continued commitment to a Western alliance built on US military might that has stood up to Moscow since World War Two.
With that, Trump moved on to the United Kingdom, where significant protests against him were expected. "Very unified, very strong, no problem". That would mark a significant milestone for the alliance.
German Chancellor Angela Merkel, who called the summit "very intense", and other leaders including French President Emmanuel Macron, played down the extent to which they had pledged to accelerate spending plans as fast as Trump wanted.
Leaving Nato would be a seismic step, previously unthinkable, that would shake up a western alliance that has endured for more than 70 years.
The United States, far the biggest economy, spent 3.6 percent a year ago, while Germany, the second biggest, paid out just 1.2 percent and only a handful of countries met the 2 percent target. He authorized previous year the deployment an additional 3,000 United States troops, bringing the total to around 15,000. The current commitment is to reach two percent by 2024 but with get-out terms that would allow some to stretch it out to 2030. "Germany is contributing troops as a lead nation in Lithuania and NATO's forward presence to the east", she said.
"President Trump's performance at the North Atlantic Treaty Organisation summit in Brussels was disappointing, yet ultimately unsurprising", McCain said. Trump said Germany was "captive" to Russian Federation, citing an energy pipeline, and used the summit to repeat calls for allies to increase their defense spending.
Earlier Thursday, Trump called out US allies on Twitter, saying, "Presidents have been trying unsuccessfully for years to get Germany and other rich NATO Nations to pay more toward their protection from Russian Federation".
The US leader held an unscheduled press conference to heap praise on himself for rallying the other 28 member states into committing to spend at least 2 per cent of GDP on defence within a "short number of years".
He continued the attack Thursday, complaining that, "Germany just started paying Russian Federation, the country they want protection from, Billions of Dollars for their Energy needs coming out of a new pipeline from Russian Federation". "I think we probably will be able to".