US President Donald Trump has called in the National Guard and ordered the deployment of emergency medical stations to coronavirus hotspots around the United States.
Mr Trump told reporters during his now-daily White House briefing on the pandemic that the federal government would pay for National Guard soldiers to be deployed in New York, California and Washington to help contain the spread of the virus.
He added that the US Army Corps of Engineers would help build the temporary medical sites in New York and that the US Navy hospital ship USNS Mercy would be deployed to Los Angeles.
"I want to assure the American people that we're doing everything we can each day to confront and ultimately defeat this horrible invisible enemy," he said.
"We're at war, in a true sense we're at war."
The US has almost 33,000 confirmed cases of COVID-19, with 409 deaths, according to a running tally by Johns Hopkins University.
Mr Trump said he had approved a request to issue a major disaster declaration for the state of New York, which has seen the vast majority of America's coronavirus cases.
He added that he had approved one for Washington state as well and would do the same for California "very shortly."
In the US Senate, partisan disagreement blocked a massive coronavirus response bill from advancing, with Democrats saying the Republican measure focused too heavily on helping corporations.
Republican US Senator Rand Paul of Kentucky on Sunday became the first member of the Senate to announce he had tested positive for the coronavirus.
'Greatest crisis since the Great Depression'
The number of cases of the highly contagious respiratory illness in the United States and Spain are exceeded only by China and Italy.
"This is going to be the greatest crisis domestically since the Great Depression," New York Mayor Bill de Blasio told CNN, referring to the economic crisis of the 1930s.
"This is why we need a full-scale mobilisation of the American military."
Mr De Blasio said New York City was not getting needed medical supplies from the federal government to contend with the rapid spread of the sometimes deadly illness.
A staffer of The Brooklyn Hospital Center opens the door for a woman being pre-screened for the Coronavirus in Brooklyn, New York Source: Sipa USA Gabriele Holtermann-Gorden/Sipa
Hospitals are scrambling for protective equipment for healthcare workers and for ventilators as they brace for a wave of patients who will need help breathing as severe cases often lead to pneumonia and decreased lung function.
New York Governor Andrew Cuomo urged the federal government to take over the acquisition of medical supplies so states do not have to compete with each other for desperately needed resources.
"Time matters, minutes count, and this is literally a matter of life and death," Mr Cuomo said.
Additional reporting: Reuters
