Face mask requirements are returning to the United States in some communities and workplaces, along with directives for mandatory coronavirus vaccinations, in a new push to curb the easily transmissible delta variant of the infection that has already killed more than 611,000 Americans. On the Independence Day holiday earlier this month, U.S. President Joe Biden heralded the strides the country had made in combating the coronavirus. But now he said he was seriously considering requiring that the more than 2.1 million federal workers be vaccinated, and that he would adhere to face mask rules when he visited parts of the country where the virus was surging. The U.S. is now recording more than 60,000 new coronavirus cases each day, the government said, up from fewer than 12,000 a day in late June. Speaker Nancy Pelosi, the leader of the Democratic-controlled U.S. House of Representatives, has reimposed a mask requirement in …