The United States on Tuesday formally rejoined the U.N.’s scientific, educational and cultural organization after a five-year absence. The U.S. return to the Paris-based UNESCO was based mainly on concerns that China has filled a leadership gap since the U.S. withdrew during the Trump administration. UNESCO’s governing board voted last week to approve the Biden administration’s proposal for the U.S. to rejoin. On Monday, the U.S. delivered a document certifying it would accept the invitation. On Tuesday, UNESCO’s Director General Audrey Azoulay said it was official. A welcome ceremony with a flag-raising and VIP guests is expected in late July….