Buy European

And that the US could ensure they can use the digital part to "turn the aircraft off" for their "national security".

No, they can't shut the software off for everyone by turning off a switch. No military in the world would ever touch that aicraft if that was the case. It is true that the F35 runs on American software (except for the Israeli variant) and that for optimal performance it requires updates that are developed by the US. But the jets aren't connected to a network in order for the US to send a malware type update to compromise the system. The updates need to be manually reviewed and installed. It's not like how Google sends out automatic updates for Android that pop up in your notification bar. That's a security risk that could be exploited by enemy agents.

And while the US can't brick the aircraft from the other side of the ocean, it can stop providing updates to the system. It would drastically reduce the aircraft's capabilities in the long term, but it would still be operational provided it has the proper maintenance. It just wouldn't be that good. To put it into crude terms, think of two gaming pcs owned by you and your friend. Both of them are top of the line and both of them can only run Windows. For whatever reason you upset Bill Gates and he refuses to send you anymore updates for your Windows and doesn't want to sell you a newer OS. Your computer works fine it's just that you can't do certain things on it because you're running Windows 7 while your buddy is running Windows 11. Might not be the best example, but that should give you an ideea.

Regardless we shouldn't stress about this. Like I've said, there's already a stealth fighter project in development at a European level and we have both the technical expertise and industrial capability to further develop. The only downside is that our stuff is more expensive since we lack the economies of scale the Americans have in the defense sector. But that can be easily solved through joint borrowing and increased investment which is what we're currently doing. The only losers here will be American defense companies that will see their sales to Europe decline as we shift to domestic alternatives.

Ironically enough Trump might be the best thing that happened for Europe since the formation of the EU. By trying to make America great again through his constant bullying tactics he is not only making America worse, but he is also making Europe great again by forcing us to loosen our ties with the US and invest in our own industries. Through sheer incompetence and ignorance that chucklenut is paving the way for us to become a superpower that can challenge US dominance over the globe.