UK's prime minister is the first foreign leader to meet US President Donald Trump since he took office last week.
UK's Prime Minister Theresa May called on President Donald Trump on Thursday to renew the "special relationship" between Britain and the United States and lead in a new, changed world.
In the United States for what will be Trump's first meeting with a foreign leader since he took office last week, May signalled a shift in foreign policy, bringing her position more in line with that of Trump.
"So we - our two countries together - have a responsibility to lead. Because when others step up as we step back, it is bad for America, for Britain and the world," May told members of Republican Party at their retreat in a speech often punctuated by applause from an enthusiastic crowd.
She urged the two countries and their leaders to stand united and confront new challenges, including the rise of economies in Asia that people fear could "eclipse the West," the threat of extremism and a resurgent Russia.
"This cannot mean a return to the failed policies of the past. The days of Britain and America intervening in sovereign countries in an attempt to remake the world in our own image are over. But nor can we afford to stand idly by."
TRT World's Simon Marks has more details from Washington.
Eager to win a trade deal
Eager to win favour -- and a trade deal -- with the new US president to bolster her hand in the divorce talks with the European Union, May said both countries shared many values and that, contrary to his statements that NATO was "obsolete," Trump had told her he was committed to the US-led military alliance.
May said she supported Trump's "reform agenda" to make NATO and the United Nations "more relevant and purposeful than they are today," and "many of the priorities your government has laid out for America's engagement with the world."
Some kind of trade agreement, though, is high on her list of priorities, despite Britain and the United States being at odds over genetically modified organisms, meat production and public procurement and May unable to sign deals until after Brexit.
May says she will launch the divorce talks by the end of March by triggering Article 50 of the EU's Lisbon Treaty, which gives up to two years to negotiate an exit deal. Only then can she agree with third countries.
Both leaders should use the time to find areas where they could remove trade barriers, May said.