Jack Johnson of the Columbus Blue Jackets, Bobby Ryan of the Anaheim Ducks, Max Pacioretty of the Montreal Canadiens, Jim Slater of the Winnipeg Jets and Jeff Petry of the Edmonton Oilers also scored for the Americans in the Group A game. Pierre-Edouard Bellemare and Nicolas Besch scored for France.
The U.S. capitalized on power-play chances in the second period and scored three unanswered goals in the third, scored by Slater, Petry and Okposo.
Besch opened the scoring in the first period, but Okposo tied the game four minutes later.
The United States will face Canada on Saturday.
The Canadians opened with a 3-2 victory over Slovakia. Jamie Benn of the Dallas Stars, Jordan Eberle of the Oilers and Andrew Ladd of the Jets scored for Canada, and Tomas Tatar and Milan Bartovic had goals for Slovakia.
Information from The Associated Press was used in this report.