NATO Secretary General Jens Stoltenberg made a similar gesture today, saying that he and Trump had a "good talk" over the phone and that they spoke about NATO's "enduring importance."
But for all those seeking reassurance, it should be noted that the man Trump tapped today to be his national security adviser, Lt. Gen. Mike Flynn, appears to have played a role in shaping Trump's controversial remarks about the 67-year-old alliance.
Flynn told ABC News this May that he first spoke to Trump in September 2015, shortly after Trump made the remark that he gets his military advice from "the shows."
"We did talk about NATO, and I told him ... NATO doesn't pay their bills," Flynn said. "The United States — we pay too much of the bill. NATO is a 20th century model and needs to be retooled for 21st century threats that we collectively face. You know, cyber is one of them. So I said those things to him when we first talked."
It was not until July 2016 that Trump raised eyebrows when he told The New York Times that he might not honor the alliance's mutual defense agreement unless other members paid their fair share. Member states are encouraged to spend 2 percent of their GDP on national defense, and now only a handful of the 28 members meet that threshold.
Asked by The New York Times if NATO members could count on the Trump administration to come to their defense if they were attacked by Russia, Trump said, "If they fulfill their obligations to us, the answer is yes."
That language stands in apparent contrast to North Atlantic Treaty, which reads, "An armed attack against one ... shall be considered an attack against them all."
In April, Trump described NATO as "obsolete."
Trump has a history of being critical of the alliance that predates his relationship with Flynn, however.
In his 2000 book, "The America We Deserve," co-authored by Dave Shiflett, it reads, "America has no vital interest in choosing between warring factions whose animosities go back centuries in Eastern Europe. Their conflicts are not worth American lives. Pulling back from Europe would save this country millions of dollars annually. The cost of stationing NATO troops in Europe is enormous. And these are clearly funds that can be put to better use."
And while Russia was sending troops into Ukraine and bombing U.S.-backed Syrian rebels, Trump often asked, "Wouldn't it be nice if we actually got along, as an example, with Russia?"
The incoming administration will soon make clear how it intends to approach NATO and Russia, and Flynn has great confidence in Trump. "I like his unpredictable nature," Flynn said, "especially as commander in chief."