British Prime Minister Theresa May and US President Donald Trump held a joint press conference on Friday during the new president's first visit with a foreign leader.

The meeting signifies a pivotal moment in trans-Atlantic relations, which were rocked by Trump's election and his controversial comments concerning NATO and the United Nations.

May told reporters that Trump was "100 percent behind NATO" and that the two leaders reaffirmed their "unshakable commitment" to the military alliance.

Trump's previous comments suggesting that Washington might not come to the aid of countries that did not meet their defense spending targets rattled European allies.