Secretary of Defense James Mattis told NATO allies on Wednesday that they need to contribute more money to the alliance's common defense if they do not want to see the United States "moderate its commitment."
Mattis raised the issue of defense spending in a closed-door meeting with senior defense officials from the 28-nation bloc, the New York Post reported. The Pentagon chief was in Brussels meeting with officials from NATO countries.
"I owe it to you all to give you clarity on the political reality in the United States, and to state the fair demand from my country's people in concrete terms," Mattis said. "America will meet its responsibilities, but if your nations do not want to see America moderate its commitment to the alliance, each of your capitals needs to show its support for our common defense."
All NATO member-states are required to spend two percent of their GDP on defense. Currently, only five of the 28 countries meet that threshold: the U.S., Greece, Poland, the United Kingdom, and Estonia.
Trump made it a cornerstone of his campaign to argue that America's allies would have pay more for their own defense to maintain the North Atlantic alliance. He suggested multiple times that, as president, he would not necessarily come to the defense of NATO allies if they are attacked by Russia.