LOS ANGELES, March 2 — The 100-day countdown to the biggest World Cup in history gets under way tomorrow against a chaotic backdrop of global unrest, from US-Israeli strikes on Iran to surging violence in Mexico and anxiety over Donald Trump’s domestic agenda.

A record 48 teams — up from 32 in 2022 — and millions of fans are set to descend on the United States, Canada and Mexico for the first ever World Cup shared by three nations.