The decision emerged one day after the U.S. flew B-52 bombers to the Persian Gulf in a show of force that was intended to caution Iran against carrying out attacks against U.S. forces or interests.
A senior U.S. military officer said the flight by two Air Force B-52s was in response to signals that Iran may be planning attacks against U.S. allied targets in Iraq or elsewhere in the region in coming days.
The United States Forces Korea says in a statement it started inoculating military and civilian health-care workers, first responders and the USFK command team with the Moderna vaccine on Tuesday.
Meanwhile, the U.S. military announced a sudden visit to the Mideast by long-range, nuclear-capable B-52H bombers, underlining America's continuing presence in the region.