US President Donald Trump has worn a facial covering in public since the beginning of the coronavirus pandemic.
The president was visiting the Walter Reed military hospital outside Washington to meet veterans.
"I think it's a great thing to wear a mask. I've never been against masks but I do believe they have a time and a place," he said while leaving the White House.
The president has previously said that he would not wear a mask.
Speaking to Fox Business Network last week, Mr Trump said: "I'm all for masks."
He added that he "sort of liked" how he looked with one on, likening himself to the Lone Ranger, a fictional masked hero who with his Native American friend, Tonto, fought outlaws in the American Old West.
But when the US Centers for Disease Control (CDC) in April began recommending people wear masks or cloth coverings in public to help stop the spread of the virus, Mr Trump told reporters he would not follow the practice.
"I don't think I'm going to be doing it," he said back then. "Wearing a face mask as I greet presidents, prime ministers, dictators, kings, queens - I just don't see it."
Some media reports have suggested aides have repeatedly asked the president to wear one in public.
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What's the current situation in the US?
The US has seen another 66,600 infections in the past 24 hours and a total of almost 135,000 deaths since the pandemic began, according to Johns Hopkins University data.
Louisiana has become the latest state to order that masks be worn indoors.
Democratic Governor John Bel Edwards also ordered the closure of bars across Louisiana, and tightened restrictions on restaurants, which will no longer be able to serve customers inside. The measures come into effect on Monday.
State Republican lawmakers are expected to oppose the move.
"If you don't like the mask mandate, then don't like it while you wear your mask," Governor Edwards said. "If you want to be mad at me about it, then be mad at me about it."
Neighbouring Texas has recorded another rise of coronavirus infections, with a record 10,500 new cases recorded on Saturday.
The governor of South Carolina has issued an order banning sales of alcohol after 23:00 in bars and restaurants to try to stop the spread of the virus.
A court in Indiana has halted the execution of a convicted killer as the victim's relatives said they were worried about travelling during the pandemic to watch him die. Daniel Lee was set to be executed on Monday in what would have been the first federal execution in 17 years.