"If your nations do not want to see America moderate its commitment to this alliance, each of your capitals need to show support for our common defence."
Earlier in the day, US Secretary of Defense James Mattis said NATO remained "a fundamental bedrock" for Washington and the transatlantic community.
The alliance remains a fundamental bedrock for the United States and for all the transatlantic community, bonded as we are together. As President [Donald] Trump has stated, he has strong support for NATO," Mattis said at a press conference.
During his presidential election campaign, Trump has repeatedly declared that NATO has become obsolete and threatened to decrease support of those European NATO states, who fail to fulfill their obligations as part of the military alliance, particularly in the sphere of defense spending.
During a press conference on January 27, as the UK PM was the first foreign minister to visit Trump at the White House, she was able to get the US president to stand behind the military alliance, which contradicts his views that NATO is "obsolete" which he expressed in the run-up to the US election.
NATO allies should carry their proportionate share of the cost for the alliance’s defense, the US secretary of defense said.
"It’s a fair demand that all who benefit from the best defense in the world carry their proportionate share of the necessary cost to defend freedom and we should never forget that ultimately it is freedom that we defend here at NATO," Mattis told reporters.