North Korea poses a constant security threat to South Korea, yet recent developments call on us -- government and public alike -- to take extra caution against possible provocations from the rogue regime.

Tension had already been running high on the Korean Peninsula since the UN imposed the harshest-ever sanctions on the North over its nuclear and missile provocations early this year.

Adding to the tension is Seoul and Washington’s decision to deploy an advanced missile defense system in the South as part of the allies’ countermeasures against the growing threat from the North.

Then there have been a series of high-profile defections by North Koreans, which South Korean officials and experts on the North believe could herald a possible implosion of North Korean society. The most recent case involved the No. 2 diplomat at the North Korean Embassy in London.

President Park Geun-hye and senior government officials take the latest case and previous defections of senior officials as a sign of serious problems brewing in the North. Park said that even the North’s “elite class is falling down” and that recent defections point to “serious cracks” in the North.

The North is highly likely to make provocations, including terrorist attacks, against the South to stir up internal unrest and cause disorder in South Korean society, the president said in a meeting with senior security aides Monday.

Park’s comments came one day after the Unification Ministry issued a similar warning. It also mentioned possible unrest in the North, saying the country was in a “very difficult situation.”

Quoting a survey of North Korean escapees, the ministry noted that economic hardship was the No. 1 factor that drove defectors, but now more North Korean defectors leave the country because they are fed up with the North’s leader Kim Jong-un and its system.

It would be hard for Kim Jong-un -- the third-generation heir of a dynastic dictatorship that has ruled the communist country with indoctrination and a reign of terror -- to sit idle while a man like Thae Yong-ho -- the diplomat in London -- turns his back on him and what the North hails as a “socialist paradise on Earth.”

The start of the annual South Korea-US military exercise Monday adds urgency to our efforts to cope with any North Korean threat. The North Korean military already threatened a “pre-emptive nuclear strike” against the South in retaliation for the two-week-long Ulchi Freedom Guardian drill, which it termed an act of “aggression.”

The North’s hostile acts could be varied: limited military strikes like the torpedoing of the Cheonan corvette and the artillery shelling of Yeonpyeongdo, and terrorist attacks in and outside South Korea, including cyberterrorism and GPS jamming.

Extra caution is needed against possible attempts to kidnap or assassinate South Koreans or North Korean escapees, for which the North already has a long track record. South Korean officials have already issued a travel advisory to South Koreans traveling to China and Southeast Asia.

Authorities should bolster security measures for those who might be targeted by North Korean agents, such as former senior North Korean officials who resettled in the South, members of civic and religious groups assisting North Korean defectors and travelers going abroad.

Travel agents report that the number of South Korean visitors to Baekdusan on the border of China and North Korea has been declining rapidly in the wake of tension on the peninsula. This is the kind of prudence ordinary citizens need to take.