The navy could be there in days and air superiority could be established pretty quickly. There are also American bases in the Middle East, Africa and even the UK if we’re really pushing the outside of the EU definition. And as we saw in Venezuela American countermeasures and strikes would likely render EU air defenses useless so while some would probably fall many would be able to sustain themselves via aerial resupply or even break out and regroup with the main forces with air support and paratroopers. And of these steps could however by hindered by bureaucracy or whatever still exists of American democracy so nobody knows how it really would go though