President Park Geun-hye said Monday that South Korea should be prepared to immediately repel any North Korean provocations, stressing it is an ominous sign that the communist nation has fired missiles and strengthened reconnaissance with drones.

In a weekly meeting with senior aides, Park also ordered officials to come up with measures to close the holes in South Korea's air defense that were revealed in the wake of findings that a series of North Korean drones flew undetected over the South on spy missions.

"Drones suspected of belonging to North Korea appeared to have spied in all directions, but our military authorities were completely in the dark about this. I think there are problems with the air defense and ground reconnaissance systems," Park said during the meeting.

Park ordered aides to work with the defense ministry to draw up countermeasures.

"We should view it seriously that North Korea has fired missiles and strengthened reconnaissance. To prepare for the possibility of additional provocations, we need to come up with measures to immediately block and repel any provocations," she said.

In recent weeks, two drones were found crashed near the border with North Korea. Military authorities later determined that the small unmanned aircraft had strong indications that they were made in and came from North Korea for reconnaissance missions.

One of the planes was found on a border island last week when the two Koreas exchanged hundreds of artillery rounds near their tense Yellow Sea border, while the other was found crashed a week earlier in a border town with a digital camera holding pictures of key facilities, including Seoul's presidential complex.

Over the weekend, a third drone was found to have crashed in an east coastal region in October last year, a revelation that heightened security worries since South Korea was defenseless for many months against such clumsily made, unsophisticated drones.

North Korea has also stepped up criticism of the South and Park, with its state media blasting her in extremely abusive language, in violation of an agreement the two sides reached in high-level talks in February to halt slandering each other.

Park said these moves could be an attempt by Pyongyang to prevent "internal instability." The totalitarian nation has often created tensions with the outside world to infuse the fear of war into its population in an attempt to tighten national unity.

"At a time like this, we need to work steadily to lay the groundwork for peace and unification," she said. "We need to step up diplomatic efforts to deter additional provocations in cooperation with the international community." (Yonhap)