'It's not possible to imagine NATO' without the US, NATO secretary general says

NATO Secretary General Jens Stoltenberg refused to answer what would happen to the North Atlantic Treaty Organization if the U.S. were to leave, in an interview with CNBC on Friday.

"NATO is about creating a framework for a strong trans-Atlantic bond, so it's not possible to imagine NATO without North America or without the United States. But I'm absolutely certain that NATO will continue because NATO has been the most successful alliance in history," Stoltenberg told CNBC.

During his meeting with German Chancellor Angela Merkel on March 17, President Donald Trump pushed "hard" in regards to NATO's commitments, said one official. In a joint press conference following the meeting, Trump said he reiterated to Merkel the U.S.'s "strong support for NATO."

Trump had called NATO "obsolete" in January, before he became president, citing that the organization hadn't defended against terrorism. He has repeatedly called on NATO allies to "pay their fair share."

The president also accused Germany of owing a great deal of money to NATO.

@realDonaldTrump: Despite what you have heard from the FAKE NEWS, I had a GREAT meeting with German Chancellor Angela Merkel. Nevertheless, Germany owes.....

@realDonaldTrump: ...vast sums of money to NATO & the United States must be paid more for the powerful, and very expensive, defense it provides to Germany!

When asked about Trump's claims, Stoltenberg said that the key aspect is for the NATO allies to implement a plan laid out in 2014 to gradually increase defense spending until it reaches about 2 percent of GDP within the decade. "And that's exactly what we are starting to do," he added.

—Correction: The full name of NATO is the North Atlantic Treaty Organization.