North Korea said Thursday it will immediately restore all military measures halted under a 2018 inter-Korean military accord after South Korea suspended part of the tension reduction deal following the North's launch of a military spy satellite.

The North's defense ministry said it will "never be bound" by the military agreement any more, effectively scrapping the deal that calls for a series of tension reduction measures along the heavily armed border, and warned that the South must "pay dearly" for its decision.

"We will immediately restore all military measures that have been halted according to the North-South military agreement," the ministry said in a statement carried by the official Korean Central News Agency.

"We will withdraw the military steps, taken to prevent military tension and conflict in all spheres including ground, sea and air, and deploy more powerful armed forces and new-type military hardware in the region along the Military Demarcation Line," it said.

South Korea must "pay dearly for their irresponsible and grave political and military provocations that have pushed the present situation to an uncontrollable phase," the North said.

South Korea partially suspended the 2018 inter-Korean military accord after North Korea launched a military spy satellite, called the Malligyong-1, on a new type of Chollima-1 rocket Tuesday night. The move allowed Seoul to immediately restore reconnaissance and surveillance operations near the border with North Korea.

Defending the satellite launch as a "legitimate" exercise of a right to self-defense, North Korea denounced the South for partially suspending the agreement for "unreasonable and illogical" reasons.

"Those of the 'ROK' will be held wholly accountable in case an irretrievable clash breaks out between the north and the south," the ministry said, using the acronym of South Korea's full name, the Republic of Korea.

The agreement, signed Sept. 19, 2018, under the previous liberal administration of President Moon Jae-in, calls for setting up buffer zones and no-fly zones near the inter-Korean border in a bid to prevent accidental clashes between the two Koreas.

Pyongyang had violated the accord 17 times until the end of last year, and 15 violations occurred last year alone, according to Seoul's defense ministry. Defense Minister Shin Won-sik had called for suspending the accord, saying it seriously limits the South Korean military's aerial surveillance capabilities.

North Korea claimed it has successfully put a military spy satellite into orbit and vowed to launch several more satellites within a short span of time to better reconnoiter South Korea and "the region of its operational interest."

The launch came amid suspicion that Russia may have provided technical assistance for the North's spy satellite in return for Pyongyang's supply of artillery and munitions for use in its war in Ukraine. (Yonhap)