Donald Trump refused to shake hands with Angela Merkel as a first meeting between the two leaders, which was postponed from Tuesday because of snow, got off to a distinctly frosty start.
The German chancellor and US president posed for the press in the Oval Office, and photographers could be heard calling for the two to shake hands. Mrs Merkel turned and smiled at her host, asking him: "Do you want to have a handshake?"
But Mr Trump, who had appeared to hold hands with Theresa May, the Prime Minister, when they walked together during her White House visit in January, looked down at the floor and avoided all eye-contact with his guest.
Mrs Merkel grimaced slightly but soon brushed off the awkward incident and began the task of attempting to build a new transatlantic partnership, quipping in their later press conference that the two leaders "will work together hand in hand".
The US president reassured her that his administration would "respect historic institutions", amid fears in Europe that he could scale back US military support for Nato, but insisted that allies "must pay what they owe".
"I reiterated to Chancellor Merkel my strong support for Nato as well as the need for our Nato allies to pay their fair share for the cost of defence," he said.
She responded by saying that Germany needed to meet Nato spending goals.
The two agreed on the need for cooperating in the fight against Islamic State terrorists in Syria, Iraq and Lybia and the peace process in Ukraine.
Mrs Merkel stressed the importance of improving relations with Russia and Mr Trump was thought to have sought ideas from her on how to deal with Vladimir Putin, the Russian president.
She also delivered a staunch defence of globalisation, and said she hoped the US and the EU could resume discussions on a trade agreement.
For his part, Mr Trump rejected accusations his "America First" agenda was isolationist and said he was only attempting to improve trade deals to protect US interests rather than pull back from the world entirely.
The question about his supposed isolationism clearly angered him, as he shot back at the reporter: "I don't know what newspaper you're reading, but I guess that would be an example of fake news."
Attempting to strike a positive tone, Mrs Merkel said it had been "much better to talk to one another than about one another".
The visit represented an opportunity for the two leaders to reset their early relationship.
On the campaign trail, Mr Trump called Mrs Merkel's migration policy "catastrophic", saying she "should be ashamed of herself" for "ruining" Germany. He lashed out at Time magazine when it named Mrs Merkel Person of the Year in 2015 instead of him.
She has been a strident critic of his Muslim travel ban and plan to build a border wall with Mexico and took it upon herself to explain the Geneva Convention to him.
The German chancellor enjoyed a warm friendship with Barack Obama and was his closest global partner. She had also worked well with George W Bush before him.
Mrs Merkel had prepared carefully for the meeting, watching Mr Trump's speeches, speaking to people who have met him and even studying a 1990 Playboy interview with the New York billionaire.
The visit was a tightrope walk for the German chancellor between building an effective partnership built on strong economic and security cooperation - especially in the context of Russia's new-found bullishness - and representing her values and those of the German people.
She is in a battle to win re-election for a fourth term later this year in Germany, where Mr Trump's historically low popularity ratings are on a par with Vladimir Putin.
Trump says Fox News wiretap claim came from 'talented legal mind'
Mr Trump is asked about the wiretapping accusations against British intelligence services.
"Very seldom, very seldom...probably wouldn't be here right now," he says, when asked if he ever rejects his tweets. There's widespread laughter as he says this.
Mr Trump goes on to say that he did not make any wiretapping claims against Britain, but that "a very talented legal mind on Fox" made those claims, and that he merely quoted this analyst.
He says questions on the issue should be put to that analyst - Andrew Napolitano - not him.
Merkel rejects idea that trade deals with Asia make workers worse off
Mr Trump is asked how he plans to make new trade deals.
"Negotiators for Germany have done a far better job than the United States. I give them credit for it. But...you look at China, virtually any country we do business with, it's not exactly good for our workers. Look at Nafta - that's been a disaster for workers."
Mrs Merkel takes the same question, and disagrees - she says that the German industry has concluded that, "actually, trade deals...with South Korea have brought us more jobs."
"We have benefited. That is the spirit which should be guiding these agreements."
Trump and Merkel clash gently
Mrs Merkel says she has not had time to discuss economic policy in detail yet.
On the impact of migration on the economy, she says it "has to be worked on, traffickers must be stopped," but that they must also look at welfare for refugees.
Mr Trump adds he has "many jobs coming back to Michigan, Ohio, places where they were losing jobs.
"But it's going to be a great policy for the United States, and worldwide."
Neither is taking the bait on questions that are repeatedly drawing attention to their numerous clashes over the past year.
"I am not an isolationist - that's fake news"
Some tougher questions now - Mr Trump is asked if his isolationist economic policy is damaging to America and to Europe.
"I don't believe in an isolationist policy, but the US has been treated very, very unfairly and that has got to stop," says Mr Trump.
He says the idea he is isolationist is "fake news."
Trump: "New healthcare plan coming along beautifully'
Now over to the floor for questions, the first one about healthcare, for Mr Trump.
He says the new healthcare plan is coming along "beautifully" and repeats claim that Obamacare was "failing miserably."
"Obamacare will fail, it will fold, it will close up very, very soon if something isn't done," he adds.
Mrs Merkel is then asked about her impression of the president.
She says that the president stands up for American interests and says she was gratified by the warm hospitality she has received.
"We are trying to address the areas where we disagree....and find a compromise. We need to be fair with each other."
Merkel: Better to talk to each other, not about each other
Mrs Merkel's turn now.
She begins: "It is much better to talk to one another, not about one another. We talked about the international situation, we discussed the shared interests that we have. "
That is no doubt a pointed references to her clashes with Mr Trump over her migration policy, and his travel ban.
Trump says "very unfair" that Nato allies do not pay their share
"I thanked the Chancellor for her commitment to spending two per cent of GDP [on Nato]," he continues.
He says that he fully supports Nato - something Mr Trump has had to stress several times, having rattled Western allies on the campaign trail with his claim that Nato was "obsolete"
Trump: US and Germany must harness power of women in economy
"It's a great honour to welcome you to the White House," begins Mr Trump, underlining their shared desire for security and peace.
He says the meeting they just had was "productive," and discussed workforce development and vocational training.
He adds that it is "crucial" that American workers are given a great employment outlook, and that this requires harnessing the "power of women" in the economy.
Press conference 45mins late
It has now been 45 minutes since this conference was supposed to start - this meeting does not appear to be going smoothly.
Merkel handshake no. 2 snubbed?
They seemed to be getting on fine earlier, enjoying a warm handshake at the White House entrance - but this press pool footage suggests Mrs Merkel and Mr Trump have already got off on the wrong foot.
A photographer can be heard asking the pair to shake hands several times in the footage - but neither of them move a muscle.
Mrs Merkel then asks Mr Trump a question, which is almost inaudible. Still no handshake.
This is unusual - both Shinzo Abe and Justin Trudeau posed for a handshake in Oval Office.
Photographers: Can we get a handshake?— David Mack (@davidmackau) March 17, 2017
Merkel (to Trump): Do you want to have a handshake?
Trump: *no response*
Merkel: *makes awkward face* pic.twitter.com/ehgpCnWPg7
Trump wants to find out how to deal with Putin
White House officials have suggested that Mr Trump is very curious to know how to tackle Vladimir Putin, the Russian president.
"The president will be very interested in hearing the chancellor's views on her experience interacting with Putin," a senior administration official told reporters.
Merkel and Trump take to Oval Office
Asked how their initial talks went, Mr Trump replied "great," adding that "many, many things" were discussed. Mrs Merkel told German reports she was glad to have had the opportunity to meet with Mr Trump.
So far, so good - but they will shorty be holding a joint press conference, at 17.20, where the questions to put to them are going to be a little bit trickier than this.
The handshake: Merkel 'deferential,' Trump 'taking power'
Donald Trump's handshakes are the stuff of legend - he almost tore the arm off Japanese leader Shinzo Abe when he came to Washington in February.
Meanwhile Justin Trudeau, the Canadian prime minister, was hailed as making the biggest "gesture of dominance in Canadian history" when he gave Mr Trump a confrontational, robust handshake during his state visit.
Theresa May went further than a handshake - she was photographed holding hands with the president.
But a body language expert told the Telegraph Mr Trump that in the case of Mrs Merkel, he came out on top.
"He's taking the more powerful position by standing in the left side of the photo (from viewers point of view) showing more of his hand and pulling her into his space," said Elizabeth Kuhnke, the author of Body Language: Learn How to Read Others and Communicate with Confidence
"In addition, by putting his left hand on her right arm, he's demonstrating power and authority over her.
"He's looking down at her while she is almost in a curtsying position. His mouth is in a tight closed smile indicating that he's holding back his emotions. Her smile is tentative. With her shoulders hunched she looks deferential. Her left hand is hanging by her side, in a lifeless position.
"He is controlling this photo op, using both of his hands to reduce her power."