This photo, taken last Wednesday, shows then Defense Minister nominee Lee Jong-sup attending a parliamentary confirmation hearing at the National Assembly in Seoul. (Yonhap)

South Korea will hold its first meeting of top military commanders under the Yoon Suk-yeol administration this week, sources said Tuesday, amid concerns about North Korea's apparent preparations for a nuclear test.

Lee Jong-sup, set to take office as new defense minister later in the day, plans to preside over the gathering Wednesday via video links, with the attendance of top officers from the Army, Air Force, Navy, Marine Corps and other military institutions, according to the sources. Yoon began his presidential duty at the start of Tuesday.

Seoul officials are paying keen attention to the possibility that the recalcitrant regime will carry out what would be its seventh known nuclear test ahead of U.S. President Joe Biden's visit to Seoul on May 20.

"We are closely tracking and monitoring movements related to key facilities and regions (in the North)," a military official here told reporters on condition of anonymity. "Our military is maintaining a firm readiness posture."

The top brass' gathering is expected to be an opportunity for Lee, a former three-star Army general, to highlight his mantle as the new minister, get a better grasp of the current security conditions and call for readiness against North Korean threats.

Lee is to take over from his predecessor, Suh Wook, who has led the defense ministry since September 2020. (Yonhap)