Four American service members and a US Forces Korea retiree tested positive for the new coronavirus upon their arrival here last month, USFK said Thursday.

The latest cases raised the total number of COVID-19 infections reported among the USFK population to 701, most of whom tested positive upon their arrival here from the United States.

Of the newly reported cases, one service member arrived at Osan Air Base in Pyeongtaek, some 70 kilometers south of Seoul, on a US government chartered flight, while the others arrived here on commercial flights via Incheon International Airport, west of the capital, according to the US military.

Two of them tested positive on their first mandatory COVID-19 test prior to entering quarantine, while the three others tested positive on a subsequent test required to exit quarantine.

All USFK-affiliated individuals arriving in South Korea are required to undergo a virus test and quarantine for 14 days. Medical personnel administer a second test prior to their release.

"Despite the recent confirmed cases, USFK remains at a high level of readiness with less than 1 percent of its active duty service members currently confirmed positive with COVID-19," the US military said in a release.

On Wednesday, USFK said it will lower the Health Protection Condition (HPCON) for Area IV that includes Gyeongsang and Jeolla provinces by one notch to the second-lowest level of "Bravo" from "Charlie" effective Monday, citing a "reduced threat of the virus" within the region.

USFK has a five-scale warning system that ranges from HPCON A to B, C, C+ and D.

Under the eased restrictions, seated dining at off-installation restaurants, domestic travel with overnight stays and shopping at indoor malls will be allowed while following South Korea's social distancing rules.

Bars, clubs and other facilities that restrict entrance to adults only still remain off limits to all USFK-affiliated personnel peninsula-wide.

"We actively consulted with the city leaders who partner with our installations, and these leaders concurred with our assessment of the current situation and agreed it is a prudent decision to adjust the HPCON level to align with the ROK government's current social distancing level there," USFK Commander Gen. Robert Abrams said. ROK stands for South Korea's official name, the Republic of Korea.

All other USFK designated areas will remain in HPCON Charlie until further notice, it said. (Yonhap)