We already don't. We want the Americans to pack up their bases and fuck off. Ami, go home! They've done enough work to stir up chaos and war all over the planet in the last 7 decades.
Germany is free to exit NATO and close Ramstein. I believe it only requires a 1-2 year notice period.
The defense budget required to operate without US assistance is another matter entirely; you’re looking at doubling existing spending, plus hundreds of billions in one-off procurement costs — and that assumes ongoing access to US weapons systems.
The US subsidizes the massive weapons development programs you currently rely on; cost sharing agreements and unit purchases do not come close to offsetting the full sunk R&D costs the US covers.
Replacing those weapons programs, and the existing US industrial base and supply chain they depend on, would run into the trillions of dollars.
Just the R&D portion of the US defense budget is $150B a year — the entire EU’s aggregate defense R&D spending is only ~€15B/year.
A truly independent EU that did not depend on the US for its security would be a very different place.
If it ends with the Navy showing its non-soft power, Europe won't have any fucks left to give about some website.