Trump meets May in 1st summit with foreign leader

US President Donald Trump today met British Prime Minister Theresa May in his first summit with a foreign leader since inauguration, hours after she called on the US and the UK to again "lead together".

May, dressed in red, was greeted in person by Trump when she arrived at the White House.

The meeting was being watched with global interest as the two countries seek to find common ground on trade and lay the groundwork for a new deal following last year's Brexit vote in favour of the UK to leave the European Union. The two countries are also looking to boost defence ties.

It was also Trump's first tryst with face-to-face diplomacy as he welcomed his first foreign visitor to the White House.

Ahead of the meeting with Trump, May, while speaking at the Republican Retreat in Philadelphia, said with the emergence of non-state actors, it is time that the countries like the US and Britain assert their leadership role.

May said Britain and the US must "lead together" again and play their role in safeguarding global security even as she welcomed the rise of democratic allies like India.

"We have the opportunity to lead together again because the world is passing through a period of change. And in response to that change, we can either be passive bystanders or we can take the opportunity once more to lead and to lead together," she said.

"New enemies of the West and our values, in particular in the form of radical Islamists, have emerged, as countries with little tradition of democracy, liberty and human rights, notably China and Russia, have grown more assertive in world affairs," May said.

"The rise of the Asian economies -- China, yes, but democratic allies like India too -- is hugely welcomed. Billions are being lifted out of poverty and new markets for our industries are opening up," she said.

May also paid her respects to the military dead of the US at Arlington National Cemetery outside Washington DC.

The UK prime minister laid a wreath at the Tomb of the Unknowns at the Virginia military cemetery, which holds the remains of unidentified US troops from the First and Second World Wars, as well as the Korean war.

Dressed in black, May was greeted by troops representing all military units based in Washington, led by Major General Bradley Becker, commander of Joint Force Headquarters for the national capital region.

A cannon was fired 19 times as the prime minister's convoy arrived at the cemetery and made its way to the memorial, which stands on a small hill looking down over serried ranks of gravestones to the monuments of Washington a few miles away across the Potomac River.

The new US president and the premier, who took office in July, both have strong political incentives to make the visit -- likely to be heavier on symbolism and aspiration than deliverables -- a roaring success.