North Korea threatened the United States on Thursday, March 7 with a preemptive nuclear strike, raising the level of rhetoric while the UN Security Council considers new sanctions against the reclusive country, Reuters reported.

North Korea has accused the United States of using military drills in South Korea as a launch pad for a nuclear war and said it will scrap the armistice with Washington that ended hostilities in the 1950-53 Korean War.

"Since the United States is about to ignite a nuclear war, we will be exercising our right to preemptive nuclear attack against the headquarters of the aggressor in order to protect our supreme interest," the North's foreign ministry spokesman said in a statement carried by the official KCNA news agency.

North Korea conducted a third nuclear test on February 12, in defiance of UN resolutions, and declared it had achieved progress in securing a functioning atomic arsenal. It is widely believed the North does not have the capacity to deliver a nuclear strike on the mainland United States.

The North's unnamed foreign ministry spokesman also said it would be entitled to take military action as of March 11 when U.S.-South Korea military drills move into a full-scale phase as it had declared the truce as invalid.

It is the latest in an escalation of tough words from both sides of the armed Korean border this week as the UN Security Council deliberates a resolution to tighten financial sanctions and a naval blockade against the North.