Defense Minister Shin Won-sik speaks during a parliamentary session held at the National Assembly, Seoul, Nov. 23. Yonhap

Defense chief Shin Won-sik said Thursday that South Korea's partial suspension of a 2018 inter-Korean tension reduction deal is "a proportional response" and "a minimal defensive measure" against Pyongyang following its spy satellite launch.

Shin's comments came hours after North Korea's defense ministry vowed to immediately restore all military measures halted under the Comprehensive Military Agreement and warned that the South must "pay dearly" for its decision.

On Wednesday, President Yoon Suk Yeol approved a motion to suspend a clause in the 2018 accord that calls for setting up a no-fly zone around the Military Demarcation Line separating the two Koreas.

"North Korea's launch of what it calls a military spy satellite on Nov. 21 is a clear violation of the U.N. Security Council resolutions and a serious provocation against the international community, once again showing it has no will to abide by the military agreement," Shin said in a parliamentary session.

"Therefore, the partial suspension of the agreement is an essential measure to protect people's lives and safety. It is a corresponding response to North Korea's provocation and a minimal defensive measure," he added.

In response to the growing threat posed by the North, Shin said the South Korean military will resume aerial surveillance operations near the border region.

"If North Korea stages provocations under the pretext of the suspension, we will respond immediately, strongly and until the end," he said.

Surveillance drones and reconnaissance aircraft were deployed near the border shortly after the suspension took effect Wednesday afternoon, according to military sources.

North Korea fired an unspecified ballistic missile toward the East Sea on Wednesday night, but the launch appears to have failed, South Korean military said. (Yonhap)