Kim, a former general, came under heavy criticism after the March sinking of the South Korean war ship Cheonan and again after North Korea struck the South’s Yeonpyeong Island on Tuesday.

North Korea has been blamed by the South and other nations for the Cheonan incident, in which 46 sailors were killed, but has denied responsibility. North Korea has blamed South Korea and the United States for the Yeonpyeong incident, in which two South Korean marines and two civilians were killed and 15 others injured.

South Korean lawmakers from both parties alleged that South Korean forces were unprepared for the North Korean attacks, and some have insisted that South Korean aircraft should have responded to the Yeonpyeong incident immediately. Lawmakers demanded Kim’s resignation earlier Thursday.

Kim actually submitted his resignation May 1, after the Cheonan incident, said the Blue House spokesman, but it was not accepted until Thursday because of the Cheonan aftermath and other military-related issues. The Cheonan sinking sparked a public uproar, with many stating that it should not have been possible for North Korea to have damaged South Korea’s military, which is much more high-tech.

Earlier Thursday, state media said North Korea will launch additional attacks on South Korea if the South continues “reckless military provocation.”

Pyongyang “will deal without hesitation the second and third strong physical retaliatory blow” if provoked, its KCNA news agency said.

As an example of provocation, it indirectly referred to a military drill that South Korea and the United States plan to hold in the Yellow Sea starting Sunday.

(Read More: CNN)