Citing what it called U.S.-led international moves to punish it for its recent nuclear test, North Korea threatened Tuesday to nullify the 1953 armistice accord that ended the Korean War.

The North also denounced joint South Korea-U.S. military exercises scheduled to start on next Monday, declaring that if the maneuvers will go ahead, it wil cut off direct phone link with South Korea at the inter-Korean border village of Panmunjom.

North Korea is known for its harsh rhetoric but Tuesday's announcement appears to be a step higher in its intensity. The two divided Korean states are technically at war, with no peace treaty signed at the end of the three-year Korean conflict. 

North Korea's military is ready to take strong countermeasures against its communist regime, according to the North's Korean Central News Agency (KCNA).

"When the war exercises turn into their main phase after March 11, the Korean War armistice agreement that has existed in its name only, will come to an end," the KCNA quoted the North's military command as saying.

Tensions run high on the Korean Peninsula following the North's third nuclear test on Feb. 12. The U.N. Security Council is currently working on a new sanctions  resolution to penalize the communist regime. 

To counter possible North Korean provocations, South Korea and the United States have tightened up their joint defense posture.

On Friday, the allies launched their annual two-month-long joint military drills, called Key Resolve and Foal Eagle, with thousands of troops from both sides involved. 

About 285,00 U.S. troops are stationed in South Korea, a legacy of the Korean War.

(Yonhap News)