North Korea on Tuesday urged all foreign companies and tourists in South Korea to evacuate, saying the two countries are on the verge of nuclear war. The new threat appeared to be an attempt to keep the region on edge over its intentions.

Analysts see a direct attack on Seoul as extremely unlikely, and there are no overt signs that North Korea's 1.2 million-strong army is readying for war, let alone a nuclear one. South Korea's military has reported missile movements on North Korea's east coast but nothing pointed toward South Korea.

'If any small incident is caused by miscalculation or misjudgment, it may create an uncontrollable situation.'—Ban Ki-moon, UN secretary general

"The situation on the Korean Peninsula is inching close to a thermonuclear war due to the evermore undisguised hostile actions of the United States and the South Korean puppet warmongers and their moves for a war against" the North, said a statement by the North Korean Asia-Pacific Peace Committee, an organization that deals with regional matters.

The statement is similar to past threats that analysts call an attempt to raise anxiety in foreign capitals. Observers say a torrent of North Korean prophecies of doom and efforts to raise war hysteria are partly to boost the image of young and relatively untested leader Kim Jong-un at home, and to show him as a decisive military leader.

Another reason could be to use threats of war to win Pyongyang-friendly policy changes in Seoul and Washington. Last week, North Korea told foreign diplomats in Pyongyang that it will not be able to guarantee their safety as of Wednesday. It is not clear what the significance of that date is.

South Korean President Park Geun-hye, who has sought to re-engage North Korea with dialogue and aid since taking office in February, expressed exasperation Tuesday with what she called the "endless vicious cycle" of Seoul answering Pyongyang's hostile behaviour with compromise, only to get more hostility.

ii-japan-interceptor-300-rt

Japan deployed PAC-3 missile interceptors in key locations around Tokyo on Tuesday as a precaution against possible North Korean ballistic missile tests. (Issei Kato/Reuters)

U.S. and South Korean defence officials have said they've seen nothing to indicate that Pyongyang is preparing for a major military action.

Despite the lack of evidence that the North is actually preparing for a war, the United States and South Korea have raised their defence postures, and so has Japan, which deployed PAC-3 missile interceptors in key locations around Tokyo on Tuesday as a precaution against possible North Korean ballistic missile tests.

Military miscalculation fears

The top U.S. military commander in the Pacific says North Korea's pursuit of nuclear weapons and long-range ballistic missiles represents a clear and direct threat to the U.S. and its allies in the region.

Admiral Samuel Locklear, commander of U.S. Pacific Command, told a Senate committee Tuesday that Kim has used the past year to consolidate his power.

Locklear says North Korea is keeping a large percentage of its combat forces along the demilitarized zone with South Korea, a position that allows North Korea to threaten U.S. and South Korean civilian and military personnel. Locklear also tells the committee that this situation creates an environment marked by the potential for miscalculation.

UN Secretary General Ban Ki-moon is warning that even a slight miscalculation involving the tensions on the Korean peninsula could spiral into an "uncontrollable situation" as he urged North Korea to tone down its "provocative" rhetoric.

He said the tensions were "very dangerous" and urged restraint: "If any small incident is caused by miscalculation or misjudgment, it may create an uncontrollable situation."

Previous eras of co-operation

Also Tuesday, North Korea said it was suspending work at the Kaesong industrial park near its border, which combines South Korean technology and know-how with North Korea's cheap labour. North Korea pulled out more than 50,000 workers from the complex, the only remaining product of economic co-operation between the two countries that started about a decade ago when relations were much warmer.

Ban, a former South Korean foreign minister, also called on Pyongyang to restart work at the complex. Speaking to reporters in Rome, Ban said the project "should not be affected by political considerations. This is purely an economic thing."

The Kaesong complex is the last symbol of inter-Korean rapprochement projects from previous eras of co-operation. Other projects such as reunions of families separated by war and tours to a scenic North Korean mountain stopped in recent years.

Even before Monday's announcement, Pyongyang had been allowing operations at the Kaesong complex to wither. Last month it cut the communications with South Korea that had helped regulate border crossings at Kaesong, and last week it barred South Korean workers and cargo from entering North Korea.

Operations had continued and South Koreans already at Kaesong were allowed to stay, but dwindling personnel and supplies had forced about a dozen companies to stop operating at Kaesong before North Koreans were told to stop working there.

North Korea briefly restricted the heavily fortified border crossing at Kaesong in 2009, but manufacturers fear the current closure could last longer.

South Korea's Unification Ministry, which is responsible for relations with the North, said 75 South Koreans at the complex were set to come home Tuesday, leaving about 400.

The more than 120 South Korean companies operating at Kaesong urged North Korea to quickly normalize operations.

"If this situation continues, companies will face the risk of going bankrupt," said Yoo Chang-geun, a vice-president of the Corporate Association of Gaesong Industrial Complex.

After an emergency meeting Tuesday in Seoul, representatives of the companies said in a joint statement that they hope to send a delegation of small- and medium-sized companies to North Korea in hopes of reopening the complex. The statement also appealed to South Korea to take a "mature, embracing posture" and work out all available measures to help normalize Kaesong's operations.