North Korea described his words as a "blunt declaration of war" and threatened stern military measures against any attempt to infringe on its sovereignty.
Now, Kim is disgracefully stepping down from the post, tattered by the North's deadly artillery attack on a border island in the tension-high Yellow Sea earlier this week and a series of slips of the tongue, at least in the eyes of presidential officials. It was the communist neighbor's second fatal military provocation against South Korea this year alone after a torpedo attack on a 1,200-ton warship, the Cheonan, in March that killed 46 crew members.
In a nighttime press briefing Thursday, President Lee Myung-bak's office Cheong Wa Dae announced its decision to "accept the minister's resignation offer" made in May to take responsibility for the Cheonan case.
The move came as a surprise, given the widely held taboo of changing a commander during battle. Tensions are sharply rising on the volatile peninsula, with the North saying it is being pushing to the brink of a war. South Korea's military has been placed to the highest crisis status following the artillery attack.
Presidential chief of staff Yim Tae-hee said Cheong Wa Dae considered a need to "change air" in the military reeling from Thursday's artillery strike that left two marines and two civilians dead.
Media here view it as de facto dismissal, however, at a time when the military faces heaps of criticism for national security loopholes and bungling an initial response to the North's latest military assault. When asked about whether media can regard Kim as being fired, Yim neither confirmed nor denied.
As the North began bombarding artillery shells onto Yeonpyeong Island in the mid-afternoon attack, the South's military took 13 minutes to return fire. Among a total of six K-9 self-propelled 155mm howitzers deployed on the island, two were reportedly out of order at that time. The military had actually detected indications of the North's potential provocation a few days earlier, according to some news reports.
Cheong Wa Dae officials said Lee was very discontent with the military's response this time and his mistrust deepened.
In his Armed Forces Day speech in September, Lee said the troops "should thoroughly figure what their problems are" and that the military should be reborn through bold reform. He added the sacrifice of 46 sailors gave bitter lessons to the South's military, which has been rather complacent amid six decades of armistice.
Experts, however, said the sudden "sacking" of the defense minister, who is known for loyalty to the conservative Lee administration, seems more aimed at heading off public criticism leveled at the Lee administration itself.
"I think the president and the administration needed a scapegoat," said Lee Sang-don, a professor at Chung-Ang University in Seoul.
He said the defense minister's comments in the National Assembly over the president's first public message on Tuesday's attack was probably the main reason for his dismissal.
South Korea grew angry over reports that upon receiving briefings on Tuesday's skirmish, the president instructed his troops to "manage the situation well to prevent it from escalating into a full-blown war." The president's comments apparently set the tone for Seoul's overall response to Pyongyang's attack and spawned criticism that the government was too passive and timid in dealing with the North's provocation.
Amid reports of casualties and video footage of burning houses and forests on Yeonpyeong Island, Cheong Wa Dae asked the media hours later to change his comments to "Deal resolutely (with the North's move) and make all-out efforts to prevent the situation from worsening."
Cheong Wa Dae officials later said the president was completely misquoted as he did not directly order to stave off the escalation of the conflict.
Defense Minister Kim revived the subsiding controversy by telling a parliamentary committee that the president's first instruction was indeed to stop the escalation of the situation. Kim added that he believed the president made the right choice.
"It is natural that Minister Kim lacks political sense as he has been a life-time soldier. Nonetheless, he seems to be held responsible for the candid remarks" that dealt a further blow to the Lee administration, the professor said.
In fact, the presidential office was often annoyed by the minister's public comments on politically sensitive issues.
Speaking to a National Assembly committee earlier this month, Kim said he "can't say that the government's decision to dispatch troops to the United Arab Emirates (UAE) has nothing to do with the exports of nuclear reactors."
His remarks bewildered Cheong Wa Dae officials, who were denying that the troop dispatch plan is associated with Seoul's contract, worth US$20 billion, with the Middle Eastern nation to build nuclear reactors there.
When a reporter asked Kim privately about Cheong Wa Dae's decision to accept his resignation, the minister only said, "I was not aware of it. I have no more to say."