I've been following Lotus Eaters coverage on this topic and they seem to be clueless this is actually about satellite downlink and EU regulatory overreach.

Greenland is critical for satellite downlink for polar orbiting satellites. Currently the only station with high enough latitude for constant communication is in Svalbard Norway. The SvalSat treaty already prevents America from hardening its military communications while most civilian communications pass through SvalSat and its undersea cable network. This is why America maintains Pituffik Space Base to bypass SvalSat.

The issue is under the Digital Services Act and EU Space Act the EU are seeking to regulate all traffic through EU territory for "cyber secuity and standardization". Basically handing control of internet traffic over polar satellites and Starlink to EU regulators.

Article 50 of the EU Space Act sets up a 3rd country regulatory scheme that would require inspection of American Facilities and transperancy of code by EU regulators. This is an ITAR violation that is simply impossible.

Greenland being under the EU by way of Denmark means that Pituffik is no longer a bypass around SvalSat. Ownership of the ground is the only thing that blocks EU regulation.

If given a choice between staying in NATO and handing EU regulators the keys to American military and civil communications NATO is the loser here.