© AFP Photo/Jung Yeon-Je
US Air Force soldiers aim their weapons behind their vehicle during a drill as part of annual joint exercises with South Korea outside a US airbase in Pyeongtaek, south of Seoul, on March 14, 2013.
Every military resource the US has, including nuclear arms, will be available to its ally South Korea in the confrontation with its northern neighbor, US Deputy Defense Secretary Ashton Carter pledged in Seoul.

"We remain steadfast to our commitment to extended deterrence offered by the US nuclear umbrella," Carter said after talks with South Korean Defense Minister Kim Kwan-Jin.

"We'll ensure all of our resources will be available to our alliance," he was quoted as saying by Yonhap news agency. Carter is visiting South Korea as part of a four-nation tour of American allies in Asia, which also includes Japan, the Philippines and Indonesia.

The veiled threat comes amid heightened tensions in the Korean Peninsula, which started with Pyongyang's third nuclear test in February. North Korea detonated a nuclear device in defiance of the UN Security Council resolution banning it from developing nuclear weapons.

North Korea insisted that it needs nuclear deterrence to guard its sovereignty against the United States, South Korea and Japan. Pyongyang claimed that Washington plans to invade North Korea, possibly using its nuclear arsenal.

After the Asian country warned that it would deliver a preemptive nuclear strike before allowing such aggression, the US said it will boost its national anti-ballistic missile system by deploying additional interceptors in Alaska. Further plans include stationing new radar facilities in Japan to monitor North Korean launches.

Previous week, Pyongyang also said it is no longer bound by the armistice agreement that ended the Korean War in 1953, a diplomatic demarche the North has used for the sixth time since 1994. Seoul is notably absent from the document's signatories, which also include the Chinese People's Volunteer Army and the US-led United Nations Command.

With tensions remaining high, some politicians in South Korea said their country needs a nuclear arsenal as well. Washington opposes further nuclear proliferation in the region, saying it can protect its ally in the event of a new war.

Seoul has also recently struck a deal with the US allowing it to deploy longer-range missiles capable of reaching any part of North Korean territory. Previously, the South had been forbidden from using such weapons as part of its military partnership with the US.