North Korea announced Tuesday a freeze in relations with South Korea and threatened military retaliation in response to alleged intrusions into its waters by the South Korean navy.

North Korea’s Committee for the Peaceful Reunification of Korea said Tuesday that it would “abrogate the agreement on non-aggression” amid heightened tensions on the divided peninsular over the sinking of a South Korean warship earlier this year.

An official South Korean report accused the Communist North of firing a torpedo at the ship, killing 46 sailors.

A North Korean military official accused the South of intruding into North Korean waters in the Yellow Sea from May 14 to 24, the Yonhap news agency reported.

“This is a deliberate provocation aimed to spark off another military conflict in the West Sea of Korea and thus push to a war phase the present north-south relations,” the official said in a statement, according to Yonhap.

Secretary of State Hillary Clinton urged North Korea Monday to reveal what it knows about the “act of aggression” that sunk a South Korean warship.

She also said the United States’ “support for South Korea’s defense is unequivocal” and that North Korea should “stop its belligerence and threatening behavior.”

South Korea has said a probe concluded the North fired a torpedo that sunk a South Korean military ship in March. The United States supports that finding, Clinton said while in China.

South Korean President Lee Myung-bak announced Monday that his country was suspending trade with North Korea, closing its waters to the North’s ships and adopting a newly-aggressive military posture toward its neighbor.

“We endorse President Lee’s call on North Korea to come forward with the facts regarding this act of aggression and, above all, stop its belligerence and threatening behavior,” Clinton said.

U.S. President Barack Obama has directed military commanders to work with South Korean troops “to ensure readiness and to deter future aggression” from North Korea.

(Source: CNN)