The head of South Korea's army, Gen Hwang Eui-don, has resigned.
Defence officials confirmed that Gen Hwang stepped down after reports in the press linked him to a financial scandal involving a property investment.
His resignation comes amid heightened tensions on the Korean peninsula after North Korea's deadly shelling of a South Korean island last month.
South Korea's defence minister resigned after criticism of his response to the attack, which killed four people.
Two marines and two civilians died in the shelling of Yeonpyeong island near the disputed Yellow Sea border on 23 November.
It was the first attack of its kind on South Korean civilians since the Korean War ended in a ceasefire in 1953.
The military has come under fierce public criticism for its perceived weak response to the attack.
Gen Hwang was promoted to the army's chief of staff in June this year. His resignation is a further blow to the South's military.
Allegations that he profited from changes to property regulations have been widely reported in South Korea.
"He judged it was inappropriate for him to stay on the post at a time when he has to lead the reform of the army," Yonhap news agency quoted an unnamed ministry of defence official as saying.
Gen Hwang is suspected of buying a property in Seoul in 2002 with advance knowledge that building restrictions would soon be eased.
The general has denied the allegations, saying he had no knowledge of the impending changes.
The BBC's Lucy Williamson in Seoul says a reshuffle of senior military staff is expected shortly.
Meanwhile South Korean live-fire military exercises entered a second day on Tuesday. North Korea has described them as a "provocation".