A US soldier tested positive for the coronavirus Tuesday, a day after arriving in South Korea, the US Forces Korea said, bringing the total number of infections among its population to 28.

He arrived at Osan Air Base in Pyeongtaek, some 70 kilometers south of Seoul, on Monday on a US government-arranged charter flight, according to USFK.

USFK said the soldier has been in isolation at a hospital on the base after being confirmed with the COVID-19 virus.

He is the fourth US soldier who has been confirmed to have contracted the virus so far, it added.

All USFK-affiliated individuals arriving in South Korea from overseas should be tested for COVID-19 and then quarantined for 14 days.

"USFK continues to maintain a robust combined defense posture to protect the Republic of Korea against any threat or adversary while maintaining prudent preventive measures to protect the force," USFK said in a release.

The US stations about 28,500 troops in South Korea to deter North Korean aggression, a legacy of the 1950-53 Korean War that ended in an armistice, not a peace treaty. (Yonhap)