Pentagon leaders said Wednesday that NATO remains vital to global security interests, rejecting Republican presidential frontrunner Donald Trump's assertion that the military alliance is "obsolete."
"NATO has played an instrumental role in Afghanistan and helping the Afghan government and the Afghan security forces restore decency and some stability in the country," Defense Secretary Ashton Carter said at an event in Florida.
"We are working with NATO now on strengthening the deterrence of Russian aggression," he added, also pointing to current NATO missions such as its patrolling for migrant-smuggling vessels in the Aegean Sea.
Trump has repeatedly criticized the North Atlantic Treaty Organization, the 28-member military alliance established after World War II to counter the Soviet Union.
"NATO is obsolete," he said in a televised interview Tuesday, suggesting that it had to be "rejiggered, changed for the better."
General Joe Dunford, the Pentagon's top officer and chairman of the joint chiefs of staff, echoed Carter's defense of NATO.
"It's hard to think about asking that question today when you look at the challenges in Europe, both to the east and the south," Dunford said.
"The relevance of NATO is not at all in question."
Democratic frontrunner Hillary Clinton has called NATO "one of the best investments America has ever made."