The Pentagon is opening military labs, deploying massive hospital ships and donating medical gear to the federal coronavirus fight that Donald Trump called "a war" on Tuesday.

Defence Secretary Mark Esper said the military will give civilian agencies as many as five million respirator masks and other items to protect emergency personnel, according to the Wall Street Journal. He also said the Defence Department will provide up to 2,000 ventilators, the newspaper reported.

In addition, the Pentagon will open up to 16 military laboratories for civilian testing, and could call up more National Guard and Reserve members to help with the response.

"It will come back very quickly once we are finished with our war with the virus," Mr Trump told reporters during a White House briefing, using military jargon to describe a fast-spreading illness. He also said the administration was also exploring setting up field hospitals to deal with the influx in patients.​

He encouraged Americans to self-isolate and “enjoy their living rooms” as more than 5,000 cases were reported across all 50 states.

It came as stark predictions were made about the impact of coronavirus.

According to Bloomberg News, Treasure Secretary Steven Mnuchin told Republican senators that up to 20% of Americans could be unemployed as a result of the pandemic.

He outlined the numbers as a worst-case scenario and urged lawmakers to take swift economic action to see it off.