The decision is the most significant since Kirsty Coventry was elected last year to serve as president of the I.O.C.

A former key aide to the Russian oligarch would face an investigation into her time overseeing the Premier League club should she return to soccer.

Fewer cities are bidding for Olympics, and those that are can’t always accommodate every event. The Milan-Cortina Games were the most sprawling Olympics in history.

Soccer’s global governing body is grappling with a World Cup first: a tournament host going to war with a participating nation.