The EU contingency for a US attack on Greenland for example is among other steps to suspend all US copyrights recognition and starve the US service industry.

Ignore patents (especially medical), licenses, royalties and such while they're at it.
Ban all travel for any muricans (they should do it anyway 'cos measles) and invite them to leave the EU.
Ignore right to repair.
Nationalize any Big US Tech assets in the EU (datacenters, wharehouses) as well as bank accounts, use them to build EU digital infrastructure.
Discourage usage of US tech (windows,AWS, etc) / encourage use of non-US tech.
Stop using USD for any trading.
Close down all US military presence or lock them in.
Etc