The United States and South Korea are deepening defense cooperation amid continued nuclear and missile provocations from North Korea.
Defense Secretary Ash Carter and South Korean Defense Minister Han Min-koo affirmed the U.S.-South Korea alliance at the Pentagon on Thursday, less than a day after Pyongyang unsuccessfully carried out yet another missile test-launch, its fifth attempted launch over the past two months.
"North Korea's nuclear tests and ballistic missile launches like the one that failed last evening threaten the stability of the Korean Peninsula and the broader Asia-Pacific region," Carter told reporters Thursday morning. "We strongly condemn last night's attempt, which even though it failed, violated several U.N. Security Council resolutions. It affirmed that this latest provocation only strengthens our resolve to work together with our Republic of Korea allies to maintain stability on the peninsula."
"The United States remains committed to defending our allies against any threat with the full spectrum of American military might," Carter continued. "Any use of nuclear weapons will be met with an overwhelming and effective response."
South Korean defense and foreign affairs leaders visited Washington on Wednesday and Thursday to discuss the future of the alliance with the United States.
Carter said Thursday that discussions centered on ensuring deterrence on the Korean peninsula as well as "opening new frontiers of cooperation in our alliance" and widening the alliance's role globally. Carter said that both countries are deepening the cooperation of their navies in maritime security and working to do more together in the cyber realm.
U.S. and South Korean forces have engaged in joint naval exercises near North Korea as a warning to Pyongyang.
The United States maintains a forward presence of roughly 28,500 American troops in South Korea in order to deter North Korean aggression. The United States also plans to deploy the advanced Terminal High Altitude Area Defense, or THAAD, missile system to South Korea in order to protect against threats from Pyongyang.
Both North Korea and China have objected to the deployment of the missile defense system.
Secretary of State John Kerry said following a meeting Wednesday with South Korean officials that the United States would deploy the THAAD system to South Korea "as soon as possible."
North Korea, which has conducted several missile tests and five nuclear tests in defiance of international sanctions, has indicated that it would launch a preemptive nuclear strike under threat from the United States.
Lee Yong Pil, a high-level North Korean official, told NBC News in an interview published Monday that Pyongyang "will not step back as long as there's a nuclear threat to us from the United States."
"The U.S. has nuclear weapons off our coast, targeting our country, our capital, and our Dear Leader, Kim Jong Un," Lee said.
"A preemptive nuclear strike is not something the U.S. has a monopoly on," he added. "If we see that the U.S. would do it to us, we would do it first. ... We have the technology."
North Korea claimed to have conducted its latest and most powerful nuclear test in September, announcing the successful detonation of a nuclear warhead that could be mounted on a ballistic rocket.
"It has led once again to the further isolation and increasing pressure, including through international sanctions, on North Korea," Carter said Thursday of the fifth nuclear test. "At the same time, it redoubles our resolve as an alliance to continue to strengthen deterrence."
While U.S. officials do not believe North Korea has nuclear weapons powerful enough to reach the continental United States, defense officials name the country among five major challenges facing America because of its nuclear ambitions.
The country's latest failed missile test-launch, which the U.S. Strategic Command said it detected early Thursday morning local time, represented the second such test in under a week.
"North Korea is determined to expand its missile threat to the peninsula, to the region, and to the United States, and our missile defenses are necessary to protect our people," Carter said. "This is a threat we need to stay a step ahead of."