Republican front-runner Donald Trump would go farther, having described the 28-state alliance as “obsolete” more than once during his push for the GOP presidential ticket. Members don’t pay up their fair share, or at all, and the clunky security organization is ill-suited for the war on terror, according to Trump. After the deadly terrorist attacks on Brussels, which just happens to be NATO’s homebase, and moves by Russian President Vladimir Putin in Ukraine and elsewhere, others have also raised questions about the relevance of the alliance in a shifting world order.

But this week while hosting NATO Secretary General Jens Stoltenberg at the White House, President Barack Obama declared NATO “…a linchpin, a cornerstone of our collective defense and U.S. security policy.” Still, influential pundits and columnists have raised legitimate concerns about NATO’s lack of agility, bloated bureaucracy and lopsided financing that leaves the military bills largely in the hands of the United States.

There have been other public figures (former Secretary of Defense Robert Gates for one) to voice dim views of NATO, originally created in 1949 after the Second World War—a time when the Soviet Union was fully intact and on a mission to expand. Which raises yet another set of questions: has NATO evolved along with the world? And is the alliance equipped to respond to modern threats?