(VOVworld) - The United States and South Korea have agreed to step up military and diplomatic efforts to counter North Korea's nuclear and missile programs, saying they posed a "grave" security threat following repeated tests this year.

US Secretary of State John Kerry and South Korea Foreign Minister Yun Byung-Se (Source: EPA/VNA)

After Wednesday talks in Washington between their foreign and defense ministers, the two countries said they will set up a high-level Extended Deterrence Strategy and Consultation Group to leverage "the full breadth of national power – including diplomacy, information, military coordination, and economic elements" in the face of the North Korean threat. US Secretary of State John Kerry said the United States would do "whatever is necessary" to defend itself, South Korea and other allies against North Korea. Kerry and US Defense Secretary Ash Carter reaffirmed that any attack by North Korea would be defeated, and any use of nuclear weapons "met with an effective and overwhelming response". Kerry and Carter reiterated the "ironclad and unwavering" US commitment “to draw on the full range of its military capabilities, including the U.S. nuclear umbrella, conventional strike, and missile defense capabilities, to provide extended deterrence" to South Korea. However, the US Secretary of State also said military efforts should be the last alternative, and Washington is working on UN sanctions against Pyongyang.