There is no hard evidence to support the theory that coronavirus spread from a lab, but the Pentagon and intelligence community continue investigating the possibility that adversaries could use it as a bioweapon.

The Defense Department has recently shifted its focus toward monitoring the possibility more closely, three people familiar with the matter told Politico.

The U.S. has reported 912,010 coronavirus cases and 51,453 deaths.

Senior Navy leaders still don’t know where the outbreak originated that spread like wildfire through the crew of the USS Theodore Roosevelt. At least 840 crew members have been infected.

Capt. Brett Crozier was accused of poor judgment and fired after the Washington Post obtained an email of his warnings about the spread of the virus on board. COVID-19 temporarily crippled the nuclear-powered aircraft carrier in the middle of a Pacific deployment. Crozier was infected, the vessel has been out of service for weeks and the crisis went all the way up the Navy chain of command.

Defense Secretary Mark Esper announced a 60-day moratorium on all international and domestic troop travel in March, delaying deployments and temporary duty assignments. Service members must do 14-day quarantines if they have to travel, including submarine crews and special operations units.

There are limitations, Esper told reporters in March. “Tell me, how do I do six-feet distancing in an attack submarine? Or how do I do that in a bomber with two pilots sitting side by side?”

Listen to GHOGH with Jamarlin Martin | Episode 70: Jamarlin Martin Jamarlin goes solo to discuss the COVID-19 crisis. He talks about the failed leadership of Trump, Andrew Cuomo, CDC Director Robert Redfield, Surgeon General Jerome Adams, and New York Mayor de Blasio.

The Navy has evacuated more than 4,200 crew members from the USS Theodore Roosevelt. That’s more than 85 percent of the crew, and they’re in quarantine, just as Crozier urgently called for.

The risk of coronavirus being repurposed as an offensive weapon increases as more is learned about the disease, and that’s likely one reason why the national security community has begun to take the possibility seriously, said Andy Weber. Weber served as assistant secretary of defense for nuclear, chemical and biological defense programs under President Barack Obama. “In terms of bioterrorism, COVID is very accessible,” he said. “Samples are available all over the world.”

The risk of COVID-19 being weaponized on a large scale is low, biodefense experts said. Because it is so infectious, attempts to spread it would likely backfire on whoever tries. But the FBI has warned local police agencies that members of extremist groups are encouraging one another to spread the virus.