North Korea warned of military action against South Korea and the United States on Monday, claiming the allied forces had brought "heavy weapons" into the DMZ truce village of Panmunjom.
Reclusive North Korea, the focus of stalled six-party talks aimed at halting its nuclear weapons programme, also said it had no choice but to bolster its nuclear deterrent in the face of a hostile United States.
The North, accused by the South and the United States of sinking one of its naval vessels in March, has already raised tension to a new height by threatening war if it is punished for the naval attack which it says was fabricated by the South.
South Korean and US forces remain in a tense stand-off with the North at Panmunjom that straddles the Demilitarised Zone after it was established at the end of the 1950-53 Korean War.
"US forces introduced weapons [to the truce village] at around 7:25am on June 26," the North's official KCNA news agency said, quoting its military, adding that the weapons must be withdrawn immediately.
"If it does not comply with the principled demand of the Korean People's Army, strong military counter-measures will be taken in the area," the agency said.
North Korea's military, with 1,2-million troops, is one of the largest in the world. The two sides are technically still at war as the 1950-53 conflict ended with a truce, not a peace treaty.
A US military spokesperson could not immediately comment on what may have occurred in the truce village on Saturday that triggered the North's comments.
On Sunday, the North rejected a call for a meeting of the commission overseeing the truce and demanded direct military talks with the South to discuss the sinking of the South Korean navy corvette in which 46 sailors died.
A delegation from the US-led UN Command is probing whether North Korea violated the armistice by sinking the Cheonan, a probe the North has denounced as a sham.
North Korea said, not for the first time, that it faced a US administration bent on imposing a nuclear threat and that it had no choice but to boster its own nuclear deterrent.
"Historical facts prove that the DPRK was quite right when it made a decision to react to nukes with a nuclear deterrent," KCNA said, referring to North Korea by its official name, the Democratic People's Republic of Korea.
"The recent disturbing development on the Korean peninsula underscores the need for the DPRK to bolster its nuclear deterrent in a newly developed way to cope with the U.S. persistent hostile policy towards the DPRK and military threat towards it."
US President Barack Obama said on Sunday the world needs to rally around South Korea in order to send North Korea a clear message over the sinking of the corvette. - Reuters