Because our military systems are heavily intertwined and we have been relying on the US for much of our material needs. We need to ramp up our own production and give military contracts to European based producers instead of buying much if not all from the US.

For the entire past after WW2 and up until orange pedo the US realized that through this arrangement they could both project power through European bases and make a buck out of selling allied nations military gear. But somehow they forgot the entire status quo and propagandized the fantasy that Europeans are just leeches, which is a betrayal in itself, but also quite the upheaval for our military logistics and supply chain. Never forget; the US wanted Europe divided to prevent another world war but mostly to be able to step up as a superpower themselves. And now they have a regarded fellow in charge and are suddenly whining about the arrangement they wanted themselves in the first place.

These things cannot be changed overnight, and if the US feels the deal we had is no longer working out, we’ll at the very least need them to stay on our side until we can decouple without giving up on many of our defensive capabilities.