At the conference that marked Trump’s first meeting with a foreign leader since his inauguration, the US president hailed the special relationship between the US and UK as “one of the great forces in history for justice and for peace”.
He also said he wanted a “quick” trade deal with Britain after it leaves the EU.
Aside an unusually subdued Trump, May also revealed that the Queen had invited Trump to visit Britain for a state visit later this year.
At the conference, British and American journalists put questions to the pair.
May called on the BBC’s Laura Kuenssberg who asked about torture, prompting Trump to joke to May: “That was your choice of question? There goes that relationship!”
He said, though he thought torture worked, he would defer to his defence secretary James Mattis.
May had earlier distanced herself from Trump’s comments, condemning the use of torture.
In another apparent climbdown, Trump reaffirmed the importance of Nato, saying he was “100% behind” the military alliance, despite questioning it during his campaign to be president.
When asked about whether he would lift sanctions against Russia, Trump said: “It’s very early to be talking about that.”