South Korea and the United States are in talks over a possible visit to Seoul by new US Defense Secretary Mark Esper as part of his first Asia trip since taking office last week, a government official here said Tuesday.

Esper is considering taking a five-nation trip to East Asia next month, which would include stops in South Korea and Japan, the official said, noting that when he visits Seoul has yet to be decided.

"I understand that (the two sides) are making the final coordination (over the time schedule and agenda)," the official said on condition of anonymity.

His trip here, if realized, would come against a backdrop of tough tasks facing the Seoul-Washington alliance, such as the envisioned negotiations over how to share the cost for the upkeep of the 28,500-strong US Forces Korea and coordination over the US push to form a military coalition to safeguard shipping lanes in the Strait of Hormuz off Iran.

When in South Korea, the defense secretary is expected to pay a courtesy call on President Moon Jae-in, hold talks with Defense Minister Jeong Kyeong-doo over the alliance issues and meet American troops.

His visit could coincide with the planned South Korea-US military exercise during which the allies would test Seoul's initial operational capability to check whether it is on course to retake wartime operational control from Washington.

Esper was sworn in as the 27th Secretary of Defense last week.

He served as acting secretary of defense from June 24 to July 15.

Prior to his inauguration as the Pentagon chief, he was the secretary of the Army. (Yonhap)