South Korea has asked the United States to increase surveillance and reconnaissance assets deployed here.

In a report to lawmakers on Monday, the Defense Ministry said it is enhancing surveillance to detect any possible North Korean threat.

Defense officials say it is possible the North will try to exploit what it might perceive as national security weakness following the impeachment of President Park Geun-hye.

Defense Minister Han Min-koo and Joint Chief of Staff Chairman Lee Sun-jin have ordered senior commanders to be fully alert and to be ready to respond swiftly.