NATO's biggest summit of the year was a win for the U.S. President, who secured the pledges of dramatically increased defense spending he has long demanded.

The President rode in on a wave of momentum, but events during his trip revealed the risks of his disruptive approach:

The leaders reaffirmed their “ironclad commitment” to NATO’s collective defense clause, Article 5. In recent years, Trump had sowed seeds of doubt about whether the U.S. — NATO’s most powerful member — would come to the aid of any ally under attack.