South Korea's top military officer on Sunday called for responding "overwhelmingly" against any enemy provocations as he visited an Air Force missile defense operations center, the Joint Chiefs of Staff (JCS) said.

JCS Chairman Adm. Kim Myung-soo made the call amid concerns of North Korean saber-rattling during the annual Freedom Shield exercise between South Korea and the United States, which began Monday for an 11-day run.

"If the enemy undertakes a provocation, don't look back and respond overwhelmingly without hesitation," Kim was quoted as saying at the second Korea Air and Missile Defense operations center at the Air Combat Command in Daegu, 237 kilometers southeast of Seoul.

The center is tasked with missile defense operations as part of the military's "three axis" deterrence system against the North, which also includes the Kill Chain preemptive strike platform and the Korea Massive Punishment and Retaliation, an operational plan to incapacitate the North Korean leadership in a major conflict.

Earlier Sunday, Kim visited the Army 2nd Operations Command, also in Daegu, where he called on troops to maintain readiness in counterterrorism and coastline border operations, his office said.

Pyongyang has long denounced the allies' exercises as rehearsals for an invasion against it, although Seoul and Washington have rejected such claims, describing them as defensive in nature.

On Thursday, the North's leader Kim Jong-un oversaw artillery firing drills, capable of striking Seoul, in an apparent response to Freedom Shield.

The JCS also detected multiple attempts believed to be made by the North to jam Global Positioning System signals around the South's northwestern border islands in the Yellow Sea from Tuesday through Thursday, although no damage has been reported. (Yonhap)