Millions of Americans have been demonstrating against police brutality and racial inequality since the May 25 killing of George Floyd, a 46-year-old Black man who died after a white Minneapolis police officer knelt on his neck for nearly nine minutes. In addition to achieving police reforms in some cities, some protesters have removed Confederate statues and other symbols of America's legacy of slavery.
Just months before November's presidential election, opinion polls in key states show Mr Trump trailing his Democratic rival, former Vice-President Joe Biden. Mr Biden wrote a Fourth of July opinion piece that struck a contrasting note with the Republican president and accused him of finding"new ways to tarnish and dismantle our democracy" every day.
On Thursday, a top US health official said he was optimistic the Trump administration's vaccine-acceleration programme"Operation Warp Speed" will generate a safe and effective vaccine for Covid-19 by year-end.