Buy European

I'll put this as politely as possible: putting words into someone else's mouth really does not convey "I do discussions well" at all, that aside:

Forcing Microsoft to just switch countries is no solution at all, the only solution is to build something here and then use it here. Free from US influence. That means no AWS, no Microsoft, no Google involvement. I'm not talking about forcing industry to switch, if they want to be dependent on foreign companies let them but there is no reason for government agencies to be at the mercy of another country.

These general rules should be followed:

• All hardware must be within the EU, run by an EU-based company (the highest parent company must also be EU-based), in today's world this is essentially critical infrastructure
• The Software chain is as follows (lowest to highest priority): hostile nations (China, Russia) - possibly hostile nations (USA) - neutral nations (Africa, most of SEA) - friendly nations (Switzerland, Norway) - EU countries
• Prevent too many soups for too few chefs, EU wide projects are to be prioritized over nation wide ones. Duplicating work is inefficient and not something that can be allowed given the current situation.

Under consideration of these the following steps should happen:
1 - migration away from Windows, most office computers can be switched almost immediately, regular office use is well supported in the Linux ecosystem
2 - immediate migration away from Windows exclusive, US based specialized Software (for example Photoshop) for Software with existing and applicable alternatives
3 - reduction of computers with Windows exclusive, US based Software where Step 2 is not possible via use on Virtual Machines, access via remote connection
4 - Collaboration with EU based companies to replace any Software from Step 3 (long term target)

Obviously what's mentioned takes time but not doing anything isn't improving the situation either and as shown by Finland increasing their Linux share from 5% at the start of the year to 20% in July Step 1 should be achievable relatively quickly, which would at least ensure governments remain operational in the, currently unlikely, case of full US hostilities.

As for the military concern: just build more factories, we've got most of the know-how we need already, just not enough production of it. There are systems we don't produce in Europe but nothing too critical, US systems in those categories can be replaced within ~5 years I recon.