Donald Trump has claimed he has managed to get Nato countries to agree to increase defence spending by $33bn.

The US President said the US “commitment to Nato remains very strong” but said he told the other members of Nato that he would be “very unhappy” if they didn’t agree to spend more. 

Speaking about countries’ contribution to Nato, Trump told reporters: “Yesterday, I let them know I was extremely unhappy with what was happening and they have substantially upped their commitment.”

Nato was now “much stronger than it was two days ago”, he said.

“I believe in Nato.”

Trump made the comments at an unscheduled press conference, delaying the end of Nato conference.

He insisted Nato leaders were now “putting up a lot” and it was “unnecessary” to pull the US out of the organisation.

He said Germany had agreed to increase “very substantially” the timescale for increasing funding.

“The people have stepped up today like they have never stepped up before,” he said.

Trump said everybody in the room had thanked him, including secretary general Jens Stoltenberg, and described himself as a “very stable genius”.

He said the secretary general gave him “total credit” for securing additional funding agreements for the alliance.

All Nato nations will be up to 2% on defence spending over a “relatively short period of years”, he said.

Russia’s annexation of Crimea was on “Barack Obama’s watch”, the President said as he insisted he would not have “allowed” it to happen.

He had earlier thrown the conference into turmoil on Thursday morning by launching into an attack on Germany and other European countries for not spending enough on defence.

The outburst came during a closed session, intended to be confined to non-budgetary issues.

An emergency session was organised in response, sources said.

During, the press conference, a reporter asked if he would change his mind as soon as he got on Airforce One. 

He replied that he wouldn’t and said that’s what other people do, that he isn’t like that.

“I’m a very stable genius”, he added.

A series of planned press conferences including those planned by both Theresa May and Angela Merkel and bilateral meetings had to be cancelled.

Trump turned up late for the morning sessions which was meant to be to discuss the accession of Ukraine and Georgia to the alliance.

The Ukrainian and Georgian leaders were asked to leave when Trump made his outburst because it was a purely Nato matter.