Media reports said that Kim, 66, had been operated on by doctors believed to be from China and France after suffering a stroke in mid-August. South Korea's largest daily, Chosun Ilbo, suggested that Kim could have partial paralysis on one side of his body, although South Korean officials seemed to be convinced that he remained in full control of the secretive communist state.
South Korean presidential spokesman, Lee Dong-kwan, said Kim "did not seem to be in a serious condition."
"We have not found anything unusual suggesting signs of leadership change in the North Korean military," Defense Minister Lee Sang-hee was quoted as saying by ruling party MP Yoo Seung-min during a closed-door parliamentary session on Thursday.
"We are prepared for any new developments," he said. "But it appears unnecessary to raise the Defcon 5 [Defense Readiness Condition] status to Defcon 3, which could trigger public concerns and irritate the North."
The statement came after South Korean President Lee Myung-bak had convened an emergency cabinet meeting late on Wednesday to discuss the consequences of any possible changes in the North Korean leadership.
"We should have thorough and precise readiness so we can respond to any situation without confusion," a presidential spokesman quoted Lee as saying.
Concern over Kim's health arose when he failed to appear at a military parade in Pyongyang marking the country's 60th anniversary on Tuesday.
"There are no problems," Kim Yong Nam, Pyongyang's No. 2 leader told Japan's Kyodo News agency.
A South Korean presidential spokesman said on Wednesday that the government had long been analyzing intelligence on Kim's health, and was "making thorough preparations for any emergency situation there."
Kim Jong-il has ruled North Korea since 1994, when he succeeded his late father Kim Il-sung, the communist state's founder. According to Soviet records, he was born in the Russian village of Vyatskoye near Khabarovsk, where his father commanded a military brigade in which Chinese and Korean exiles served.
