The United States flew surveillance aircraft over South Korea on an apparent mission to monitor North Korea, a military source said Wednesday, amid escalating tensions between the two Koreas.

"The US Navy's EP-3E and US Forces Korea's RC-12X were spotted flying over the capital area," the source said.

The flight came as North Korea has been ratcheting up tensions on the peninsula, signaling a move to abolish an inter-Korean military tension-reduction deal signed in 2018.

Earlier in the day, the North's Korean People's Army said it will redeploy troops to an inter-Korean industrial park in the western border town of Kaesong and the Mount Kumgang joint tourist zone on the east coast.

The North also said it will restore guard posts removed from the Demilitarized Zone separating the two sides and resume all kinds of regular military exercises near the inter-Korean border in violation of the military agreement with the South.

The defense ministry expressed "deep regrets" over the North's announcement and warned it will make sure that Pyongyang pays the price if it actually takes military action against the South. (Yonhap)