Why is the European Union (445million) + UK (68 million) so petrified of Russia (145 million) that they need the US to bear the load of their defense? Sure, Russia has nukes, but so do France and UK, and they would likely lend a few to Germany if needed. Moreover, Russia's economy is moribund in all aspects except oil and gas.
Bring the troops back home. Give Euroland thoughts and prayers and "support from behind" as the Sainted One used to say.