WASHINGTON -  US President Donald Trump and British Prime Minister Theresa May have reaffirmed their commitment to the Nato alliance after White House talks on Friday.

Mrs May confirmed Mr Trump was "100 percent behind Nato" despite the American president's recent comments calling the transatlantic alliance obsolete, reported BBC.

President Donald Trump was also asked about his plans on sanctions against Russia at a joint press conference with British Prime Minister Theresa May on her visit to Washington - the first foreign leader to be welcomed by the president.

Trump said he wants a "great relationship" with Russia, but would not say if he would lift US sanctions against the country.

Trump and Russian President Vladimir Putin will speak on Saturday (today), according to the White House and Kremlin. They are expected to discuss bilateral affairs and national security in the first call since the inauguration. But Trump said it was "very early" to talk about the sanctions imposed on the country by his predecessor, former president Barack Obama.

"We will see what happens," said Trump. "We look to have a great relationship with all countries, ideally. That won't necessarily happen, unfortunately, [and it] probably won't happen with many countries.

"But if we could have [a relationship] as we do with Prime Minister May… if we can have a great relationship with Russia and with China and with all countries, I am all for that.

"That would be a tremendous asset. No guarantees, but if we can, that would be a positive, not a negative."

May said Britain had been "very clear" that sanctions should remain in place until the Minsk agreement, stopping the war between Russia and Ukraine, had been fully implemented.

Republicans have expressed opposition to any softer White House line against Moscow. Senator John McCain - a vocal critic of Mr Putin, who has called him a "thug" - said that would be a "reckless course" and he would pursue legislation to enforce the sanctions.

Trump has been bedevilled by criticisms that he has too close a relationship with Putin, inflamed by intelligence reports of Russian meddling in the US election and an ongoing investigation into ties between Russia and former Trump campaign aides.

While the new president may see sanction-removal as the first step in forging closer ties with a former adversary, the move could come with at a high political price.

Kremlin spokesman Dmitry Peskov confirmed the phone call between Mr Trump and Mr Putin, but said it was unlikely to result in any specific agreements. But Trump adviser Kellyanne Conway told Fox News on Friday that removing US sanctions on Russia was "under consideration".

TRUMP PHONES MEXICAN PRESIDENT

President Trump spoke by phone for an hour Friday with Mexican counterpart Enrique Peña Nieto, a day after a dispute over Trump's proposed border wall caused a rift between their two countries and cancellation of a scheduled meeting between the two leaders.

Saying he had "a nice phone call" with Peña Nieto, Trump told reporters he would continue to push for talks with Mexico on trade rules and how Mexico might pay for the wall, despite that government's insistence that it would never help finance such a structure.

"We'll be negotiating and we'll see what happens," Trump said during a joint news conference with British Prime Minister Theresa May.

Trump said nothing about the possibility of re-scheduling the meeting with Peña Nieto. A Trump administration official confirmed the one-hour call took place Friday morning.

For its part, the Mexican government said that Trump and Peña Nieto agreed during their call not to publicly discuss the call, though Trump did plenty of talking about his issues with the nation's southern neighbour.

Just before the call, Trump sent out a tweet again criticizing Mexican trade and migration: "Mexico has taken advantage of the U.S. for long enough. Massive trade deficits & little help on the very weak border must change, NOW!"

Repeating that sentiment during the news conference, Trump said the Mexicans have "out-negotiated us and beat us to a pulp ... The United States cannot continue to lose vast amounts of business, vast amounts of companies, and millions and millions of people losing their jobs. That won’t happen with me."

He added: “The border is soft and weak and drugs are pouring in, and I’m not going to let that happen."

On Thursday, Peña Nieto insisted his country would never pay for the wall as he announced he would not travel to Washington for a Trump meeting that had been set for Tuesday.

Later that day, the Trump administration floated the idea of a 20 percent tax on Mexican imports to pay for the wall, though it later pulled back and said that is only one of several options.