South Korea has named a former chairman of the joint chiefs of staff as its new defence minister, amid mounting criticism of the government's response to shelling by North Korea.
Four people were killed by shellfire from the north on the island of Yeonpyeong in the Yellow Sea on Tuesday.
Kim Kwan-jin, 61, replaces Kim Tae-young, who resigned after criticism that he was too slow to respond to the attack on Yeonpyeong.
A presidential statement says the appointment will boost morale in the military and restore the trust of the people.
The BBC reports the barrage of shells was one of the worst incidents since the end of the Korean War in 1953, which concluded without a peace treaty.
US commander in South Korea, General Walter Sharp, said Tuesday's attack was a clear violation of the 1953 armistice.
South Korea is changing its rules of engagement to allow it to respond more forcefully to similar incidents.
New warning by North
Meanwhile, North Korea has warned that joint-military exercises between the South and the United States, beginning on Sunday in the Yellow Sea, will push the peninsula to the brink of war.The official KCNA news agency said:
"The situation on the Korean Peninsula is inching closer to the brink of war
due to the reckless plan of those trigger-happy elements to stage again war exercises targeted against the [North]."
The BBC reports fresh artillery-like sounds were heard on North Korean territory close to Yeonpyeong on Friday.
China on Friday issued a warning against military activity in the region. In a statement, the foreign ministry said:
"We hold a consistent and clear-cut stance on the issue. We oppose any party taking any military actions in our exclusive economic zone without permission."
That zone extends 320km from China's coast and includes areas south of Yeonpyeong.