The deadly coronavirus has now hit all 50 states in the US as West Virginia reported its first case of the infection on Tuesday.
Announcing its first Covid-19 patient, West Virginia Governor Jim Justice said: “We knew this was coming.”
New York City said it is considering a lockdown similar to one in the San Francisco Bay area.
There have so far been 108 deaths in the US from coronavirus and more than 6,300 confirmed cases nationwide.
Globally, there are almost 200,000 cases and nearly 8,000 people have died.
US Vice-President Mike Pence said the White House may call on the US military to establish field hospitals in virus hot zones if requested by state governors.
He told a White House news conference on Tuesday that the Army Corps of Engineers could be asked to set up field hospitals, known as MASH (mobile army surgical hospital) units, or help expand existing hospitals.
Pentagon chief Mark Esper said the US military would make available five million respirator masks and up to 2,000 ventilators to the US health department.
He said the military would also open its 14 certified coronavirus testing labs to test non-military personnel.
President Donald Trump – who is seeking re-election in November – told a press briefing on Tuesday afternoon that travel restrictions within the US were on the table.
“You can do a national lockdown,” Mr Trump said. “Hopefully, we’re not going to need that. It’s a very big step.”
He also defended his tweet on Monday calling the infection the “Chinese virus”, which his critics said was racist.
“It did come from China,” he told reporters.
Mr Trump also said on Tuesday of the outbreak: “I’ve felt that it was a pandemic long before it was called a pandemic.”
Last month he struck a more optimistic tone, saying the US coronavirus outbreak “within a couple of days is going to be down to close to zero”.
Source: BBC News