Insane threats can escalate worldwide unless properly identified and countered at the right moment. That was the case with Germany's 1939 invasion of Poland and Japan's 1941 attack of the Pearl Harbor. The world is now nervous around North Korea's nuclear and missile threats.

Pyongyang's recent posturing is not confined to the Korean Peninsula. It threatens Japan and the United States and even China and Russia. The North has snubbed a UN Security Council resolution condemning its long-range missile launch and demanded an apology.

If the appeasement of the Chamberlain government encouraged Hitler's expansionism and if traditional American isolationism enticed Gen. Tojo's adventures for the Greater East Asia Co-Prosperity Sphere, what is nurturing the irrational provocations of the Kim Jong-il regime in its pursuit of the fantasy of "a great, prosperous and powerful nation"?

The basic reason, needless to say, is the appeasement policy adopted by the last two leftwing administrations. But there are other important reasons elsewhere. The selfishness and irresponsibility of some  countries with veto power at the UN Security Council and the consequent lethargy and incompetence of international agencies including the UN have helped make North Korea what it is today.

North Korea, making the most of the international environment, is rushing toward the year 2012, set as "the year of opening the gate to a great prosperous and powerful nation." Seoul, meanwhile, is busy preparing for the same year, when Korea-U.S. Combined Forces Command will be dissolved.

We cannot simply ignore the North’s provocations. Just because no extraordinary military movements are detected off the west coast and along the demilitarized zone, we should not regard the North Korean Army General Command's Jan. 17 declaration of "advance to general confrontation posture," and a series of statements issued thereafter merely as brinkmanship in negotiations with the South and the U.S.

What we should pay attention to is what the military has done in waters off the west coast in the past decade. Following the first Yeonpyongdo naval skirmish in June 1999, the North Korean military declared a maritime border in the West Sea, and "the order of navigation to and from the five West Sea islands," which are under the jurisdiction of the South. The North has unilaterally built up legal rights it can claim later.

North Korea has stepped up measures this year. On Jan. 30, the Committee for the Peaceful Reunification of the Fatherland declared null and void all political and military accords reached between the two Koreas as well as clauses concerning the Northern Limit Line, the de facto maritime border, stipulated in the annex agreement on non-invasion of the two Koreas. On May 27, the North Korean Army said in a statement it will not be bound by the armistice agreement any longer and that the Korean Peninsula is at war.

The North Korean military has taken systematic and target-oriented military measures against the South. It has prepared its own legal grounds and justifications for carrying out provocations against the South at any time. Pyongyang has built up its own grounds to define our Navy's routine guard actions in waters off the west coast as a military provocation and use it as an excuse to attack.

We must prepare. It is not a question of if but of when. An unexpected landing on our islands off the west coast could happen at any time.

By Park Yong-ok, a professor at the Hallim Institute of Advanced International Studies