Britain's May Says Trump Backs NATO '100 Percent'

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WATCH: Trump, May Talk Security, NATO, And Putin

WASHINGTON -- British Prime Minister Theresa May says U.S. President Donald Trump stands fully behind NATO, an alliance whose usefulness he has previously questioned.

Standing next to Trump at a news conference in the White House on January 27, May said her counterpart confirmed during their meeting that he was "100 percent behind NATO."

"On defense and security cooperation, we're united in our recognition of NATO as the bulwark of our collective defense, and today we've reaffirmed our unshakable commitment to this alliance," said May, who became the first foreign leader to meet Trump after his inauguration last week.

NATO members in Eastern Europe have been rattled by previous comments Trump has made about the alliance, including that it is "obsolete."

Many of those members are concerned about Russia's intentions in the region following its 2014 annexation of Ukraine's Crimea territory and backing of separatists in eastern Ukraine.

Trump, who last year suggested Washington might not defend NATO members who do not allocate enough defense spending, says he wants to improve battered bilateral ties with Moscow.