President Donald Trump has stood by claims he was wiretapped under Barack Obama, telling visiting German Chancellor Angela Merkel: "At least we have something in common, perhaps."
Mrs Merkel visited the White House for a key summit with Mr Trump, in their first face-to-face meeting.
Nato, trade and Ukraine were high on the agenda, but the focus was on how two leaders with contrasting ideas and leadership styles would interact.
`Something in common` on wiretapping - Trump
Mr Trump said he "very seldom" regrets anything he tweets, brushing off questions about his claims without evidence that his predecessor, Mr Obama, wiretapped him during last year`s presidential campaign.
Mr Trump said of Mrs Merkel that "at least we have something in common", referring to a US acknowledgement in 2015 that the German Chancellor`s phones were tapped.
Congressional leaders from both political parties have said they did not believe Trump was wiretapped.
Mr Trump deflected criticism about Press Secretary Sean Spicer, who on Thursday repeated a charge that a British intelligence agency had helped Mr Obama wiretap Mr Trump.
Mr Trump said Mr Spicer was merely quoting a Fox News analyst when he made the comments.
UK communications intelligence agency GCHQ rejected Mr Spicer`s allegations as "nonsense".
No. 10 Downing Street asserted Mr Spicer had agreed not to repeat the claims. The White House said Mr Spicer was "simply pointing to public reports, not endorsing any specific story".
However, former foreign secretary Sir Malcolm Rifkind said it was not enough to promise not to repeat the allegation. "That`s not the same as saying it was rubbish in the first place," he said.
Mr Trump refused to apologise for the accusation.
Trade on the agenda
Mr Trump expected the United States to do "fantastically well" in trade with Germany, he said at a joint news conference, while also pushing for NATO-aligned nations to help pay for the organisation`s peacekeeping efforts.
"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 defense," he said.
Mr Trump said he did not believe in isolationism, but that trade policy should be fairer.
Mr Merkel said she hoped the US and the European Union could resume discussions on a trade agreement and that she had told Mr Trump Germany needed to meet NATO spending goals.
"We held a conversation where we were trying to address also those areas where we disagree, but we tried to bring people together ... tried to find a compromise that is good for both sides," she said.
The visit was scheduled for Tuesday, but was postponed because of a snowstorm.
Past criticisms swept aside
Mr Trump earlier greeted the long-serving stateswoman at the White House with a handshake before they began talks in the Oval Office. Both leaders described their meeting as having been good.
The meeting, between two leaders who have not always agreed, is consequential for both sides.
Mrs Merkel needs to walk a diplomatic tightrope, building a relationship with Mr Trump without appearing to sacrifice her own values or disappoint her supporters as she prepares for an election at home seeking a fourth term as chancellor.
In January, Mr Trump said the German chancellor had made "a catastrophic mistake" by allowing hundreds of thousands of refugees and migrants into Germany.
And when Time magazine chose her as its person of the year in 2015 instead of him, Mr Trump said she was "ruining Germany". However, he had also said in the past she was a leader he greatly respected.
For her part, Mrs Merkel has criticised Mr Trump`s controversial travel ban that targets the citizens of several mainly Muslim countries.
In her first telephone conversation with Mr Trump after he took office, she explained that the Geneva Convention obliges signatories, including the US, to take in refugees of war on humanitarian grounds.
However, she had close relations with Mr Trump`s predecessors, Barack Obama and George W. Bush, and is likely to seek a strong working relationship with him despite major policy differences and wariness in Germany about the former New York businessman.
Source: Reuters / BBC