U.S. President Donald Trump hailed a personal victory at a NATO summit on Thursday, saying allies had sharply increased defense spending commitments after he provoked a crisis session with a tirade at European leaders.

Officials at the meeting said Trump had shocked many present and broke with diplomatic protocol by addressing German Chancellor Merkel by her first name, telling her: "Angela, you need to do something about this."

"We had a very intense summit," Merkel herself told reporters after the meeting.