The move is the latest development in the dispute over how much Seoul should pay for the U.S. troop presence.
Aggressive efforts by the U.S. military in South Korea appear to be working against COVID-19.
North Korea hasn't reported any cases of the coronavirus, formally known as COVID-19, which has spread worldwide.
"The Army's order is in effect immediately through May 6, 2020, or until further notice," USFK said
Humphreys garrison commander Col. Michael Tremblay said the South Korean woman took the COVID-19 test on Thursday.
The launches came two days after North Korea’s state media said leader Kim Jong Un supervised an artillery drill.
North Korea reported its drills two days after the U.S. and South Korea postponed joint exercises due to coronavirus fears.
The top U.S. commander in South Korea also raised the risk level for the military community on the peninsula to moderate.
The exercises are held throughout the year and are intended to prepare troops for potential combat against North Korea.
"The situation is quite serious," U.S. Defense Secretary Mark Esper said.