His remarks come as the US and others have reinforced Nato’s eastern flank amid the war in Ukraine.
The stop at an airbase in Rzeszow, near the Ukrainian border, was part of Mr Biden’s trip to Europe to rally allies.
However, back home Mr Biden faces scepticism over his Ukraine response.
In his remarks to the troops on Friday, the president sought to portray their deployments as part of a wider “fight between democracies and oligarchs”.
