The US is the largest arms dealer in the world and sells ass tons of equipment to the EU. Ain't nobody going to be buying US arms if they think they could be cut off on a whim. Large parts of the US economy are based on arms production and sales, and a large part of the US's non-arms trade is thanks to the US protecting its trade routes and partners. If the US stops protecting its trade, people will stop preferring trade with the US because it will now be vulnerable and near impossible to secure as a smaller nation because it has to cross the largest oceans in the world.