North Korea’s neighbors reacted swiftly Monday to the death of Kim Jong Il, with close ally China expressing shock, and U.S. military allies South Korea and Japan holding high-level security meetings.
Beijing offered its "deep condolences" on the death of the North Korean leader, a foreign ministry spokesman said, Chinese state news agency Xinhua reported hours after Pyongyang's state media said Kim succumbed to a heart attack.
"We are shocked to learn that DPRK top leader comrade Kim Jong Il passed away and we hereby express our deep condolences on his demise and send sincere regards to the DPRK people," foreign ministry spokesman Liu Weimin said.
China is a top ally of the nuclear-armed nation and some analysts had speculated that Beijing feared any crisis that might arise over Kim's succession.
North Korean media said Kim's son, Kim Jong-Un, in his 20's, would succeed him. He was named heir apparent last year.
China's state CCTV television network showed footage of North Koreans weeping on the streets.
South Korea
North Korea's arch rival South Korea ordered its military on emergency alert and stepped up border surveillance, following the announcement of Kim's death.
President Lee Myung-bak called a meeting of the National Security Council as some officials speculated whether Kim Jong-un will take over the country as planned.
"Because of the surprise death of Chairman Kim, the North's top leadership is believed to be left in a state of enormous shock and confusion,” Won Yoo-chul, head of the South Korean national assembly’s defense committee, told Yonhap News Agency.
Seoul has increased air patrols and also asked its U.S. ally, which has 28,500 troops in the South, to step up surveillance by planes and satellites.
Lee had a phone conversation with U.S. President Barack Obama a couple of hours after Kim's death was announced and they "agreed to closely cooperate and monitor the situation," a presidential spokesman said.
"Monitoring and security around border areas has been strengthened. We are paying close attention to any movements by the North's military," a South Korean defence ministry spokesman told Agence France-Presse.
However, no signs of military activity have been observed along the border, which is the most heavily militarized in the world.
Attack
Last year, North Korea launched a deadly artillery attack on its southern neighbor's Yeonpyeong island.
Stocks also tumbled in South Korea, which has remained technically at war with the North since the three-year Korean War ended in only an armistice in 1953.
The South Korean won sank to a two-month low, as the leader’s death triggered uncertainty in the region.
Japan, which has no diplomatic relations with Pyongyang, also called an emergency security meeting and beefed up intelligence gathering on North Korea.
Prime Minister Yoshihiko Noda told ministers to prepare for any unexpected circumstances, including financial or border issues.
Japan’s top government spokesman, Osamu Fujimura, expressed condolences to North Korea over Kim's death and hoped there will be no "adverse" security developments.
"The Japanese government hopes that this unexpected development would not bring any adverse impact on the peace and stability of the Korean peninsula,” he said.
Japan's ties with North Korea have long been fraught due to Pyongyang's bitterness over Japan's 1910-1945 occupation of the Korean peninsula and Japanese anger over the abduction of its citizens by North Korean agents decades ago.
Missile
Japan also worries about North Korea's missile and nuclear programs, which began under Kim Jong Il’s reign.
The future of North Korea’s nuclear program remains up in the air as Kim's death came as Pyongyang proposed the resumption of denuclearization talks.
North Korea had walked out on the Six-Party talks—which include the two Koreas, China, Japan, Russia, and the U.S.— in 2008, but in August, Kim agreed to consider a moratorium on nuclear tests and return to the stalled talks.
Reported by Rachel Vandenbrink from Tokyo.