Donald Trump refused to commit to NATO's 'collective defence' clause in unsettling comments to allies ahead of today's summit in the Hague.
'Depends on your definition,' he told journalists in comments sure to rattle the European allies he dined with upon arrival in the Netherlands.
'There's numerous definitions of Article Five. I'm committed to being their friend.'
Article Five is a founding principle of the NATO military alliance, requiring allies to treat an attack against one as an attack against all.
It has only been invoked once, after the 9/11 terrorist attacks against the United States. Allies stepped in to provide support for the U.S.
