A Korean Air flight attendant who worked flights from Los Angeles International Airport has been infected with the deadly coronavirus, according to South Korean national daily newspaper, JoongAng Ilbo.

The attendant, 24, was confirmed that to contracted the virus on Tuesday. Local media reported that the woman serviced flights from Seoul–Incheon International Airport to Los Angeles International Airport between February 19 and 20. She also worked a flight from Tel Aviv, Israel, to Seoul on February 15, according to South Korea’s Center for Disease Control. Korean Air has shut down its operations center at the Seoul airport to quarantine the area.

As of Wednesday, 1,200 people in South Korea have been diagnosed with the coronavirus. The illness has killed 11 people there.

As the new coronavirus, which was first found in China, has begun to sweep through South Korea, soldiers stationed in close quarters on bases throughout the country are at particular risk. Already 20 South Korean soldiers and one American have tested positive.

In response the allies are taking aggressive measures to guard against a viral outbreak and are even considering curtailing a key joint military exercise, something experts say is inevitable because if the virus were to spread through the ranks it could significantly weaken their ability to fight if necessary.

“In the military, soldiers are living as a group. So even if just one person contracts the virus at his base, its aftermath would be really tremendous,” said Kim Dae-young, an analyst at the Korea Research Institute for National Strategy. “This year, no military training can be the best option.”

The virus has infected more than 80,000 people worldwide, mostly in China, though over the past week South Korea has become the second-worst affected country after an outbreak centered in the southeast around its fourth-largest city, Daegu.

South Korea boasts a 600,000-strong military, while the U.S. stations 28,500 troops in the country largely as a deterrent to possible North Korean aggression. Daegu, with a population of about 2.5 million people, is near four American bases.

The United States Forces Korea on Monday said that a USFK widowed dependent tested positive for the virus. On Wednesday the U.S. reported that a 23-year-old soldier had tested positive and would be treated at Camp Humphreys near Seoul. It said the soldier was originally based at Camp Carroll near Daegu.

The Associated Press contributed to this report.