Bidding farewell but vowing to return “in some form,” U.S. President Donald J. Trump boarded the White House’s Marine One chopper for the last time on Wednesday, ascending into the winter sky and begrudgingly passing the torch to Joseph R. Biden, the country’s new commander in chief.

After four years in office, Trump’s presidency ended with turbulence: More than 400,000 people have died from COVID-19 in the country, the statehouse was violently ransacked by some of his supporters, and House members voted to impeach himin the twilight of his term. All of this could distract President Biden, a foreign