WASHINGTON (Reuters) - U.S. Defense Secretary Mark Esper said on Tuesday he was extending an order to the U.S. military to halt travel and movement abroad, and noted it was unclear how long coronavirus-related restrictions would remain on military personnel.

“We don’t know how this will play out,” Esper told reporters at the Pentagon, adding that the military would review the issue every 15 days. The stop movement order was set to expire on May 11.

“Before I start moving people around ... I want to make sure I can do it with a high degree of confidence that it will not further spread the virus and contaminate units and communities,” he added.

The order illustrated the Pentagon’s growing concern about the rapid spread of the virus, which has infected about 2,600 U.S. troops.

Esper also said that in New York the military was working toward moving military doctors and nurses, including some from the hospital ship Comfort, to overstretched hospitals.

“They have the bed capacity but what obviously has become strained, stressed, are these hardworking nurses and doctors and respiratory therapist,” Esper said.

“That’s where we’ve now pivoted in the last week or so to move our doctors,” he added.

Until recently, the Pentagon had focused on increasing New York’s bed capacity to help ease the strain on hospitals.

While the number of military personnel testing positive for the virus has increased, officials are also looking at the number of asymptomatic cases.

Of the roughly 585 personnel who have tested positive for the coronavirus onboard the aircraft carrier Theodore Roosevelt, only about 213 are symptomatic, Esper said.

He added that the Pentagon was looking to ramp up testing of personnel in military labs.