Miles Wood and Chris Wideman opened up the scoring for the U.S. in the first period, while Dylan Larkin, Noah Hanifin and Auston Matthews added to the scoreline in the second.
Matthews added another goal in the third to give the Americans their first victory of the campaign.
Wideman, Larkin and Matthews all scored on power plays in chippy contest marked by numerous penalties.
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Elsewhere in Group B, Slovakia beat Hungary 4-1, while France needed a shootout to defeat Germany 3-2.
Kazakhstan won a match in the world championships for the first time in a decade with their 3-2 shootout triumph over Switzerland.
The Czech Republic remained perfect in Group A after beating Latvia 4-3 via shootout, while Denmark overcame Norway 3-0.
(Reporting By Dmitriy Rogovitskiy; Editing by Larry Fine)
