Because the World Cup group is decided by lottery. It is not artificially divided. If the United States and Iran draw a group, they must play in the same group. As long as you participate in the World Cup, you must abide by the rules of the World Cup.
The FIFA World Cup, referred to as the World Cup, is the most famous and influential football match in which teams from all over the world participate, symbolizing the highest honor in football. The World Cup has more than 3.5 billion TV viewers worldwide.