Obama made the remarks at a press briefing at the White House just before departing on his last trip overseas as president — an opportunity he'll take to signal "solidarity with our closest allies," he said.
"In my conversation with the president-elect, he expressed a great interest in maintaining our core strategic relationships, and so one of the messages I will be able to deliver is his commitment to NATO and the trans-Atlantic alliance," Obama said.
"I think that's one of the most important functions I can serve at this stage during this trip, is to let them know that there is no weakening of resolve when it comes to America's commitment to maintaining a strong and robust NATO relationship and a recognition that those alliances aren't just good for Europe," the president added. "They are good for the United States, and they are vital for the world."
"If they fulfill their obligations to us, the answer is yes," Trump told The New York Times in July when asked if he would defend the Baltic states from an attack by Russia.
Stoltenberg issued a stark reminder, seemingly aimed at Trump, that NATO's mutual defense clause has been invoked only once: when NATO allies deployed in support of the United States after the terrorist attacks of Sept. 11, 2001.