US President Donald Trump posted a photo of himself wearing a mask on Monday, saying that it is "patriotic" to do so.
"Many people say that it is patriotic to wear a mask when it is impossible to exercise social distancing. And nobody is as patriotic as me," Trump posted on Twitter.
It comes just days after he ruled out imposing a national mandate requiring people to wear face masks in public in order to stem the spread of the novel coronavirus.
Trump had until now avoided being seen with a face mask and was only pictured with one on earlier this month. The issue has become highly politicised in the country with some arguing being forced to wear a mask infringes on their constitutional rights.
Trump himself appeared to mock Joe Biden, his main Democratic rival for the presidential election, earlier this year for wearing a face mask.
The US is the world's most severely-hit country with more than 140,000 fatalities and 3.8 million cases recorded since the beginning of the outbreak, according to a tally by Johns Hopkins University.
The head of the US Centers for Disease Control and Prevention, Robert Redfield, wrote in an editorial released on July 14 in the JAMA medical journal that "the time is now" for universal masking.
"The public needs consistent, clear, and appealing messaging that normalises community masking.
"At this critical juncture when COVID-19 is resurging, broad adoption of cloth face coverings is a civic duty, a small sacrifice reliant on a highly effective low-tech solution that can help turn the tide favourably in national and global efforts against COVID-19," he added.
France and the UK have both made wearing face coverings on public transport and other public spaces mandatory.