Theoretically yes. This is an issue that has been considered before, though admittedly not with regards to fucking Greenland. Turkiye and Greece have long been enemies as well as members of NATO, and it’s been considered that the invocation of Article 5 by the aggressed-upon party against the aggressing party in case of a serious war would, theoretically, be binding on the other members of NATO.
In practice, NATO is a gentleman’s agreement with no means of enforcement. Everything comes down to political will - NATO is just an organizational structure to facilitate a response. It cannot replace the will (or lack thereof) of national governments.
To your point, I think the political will to defend Greenland will definitely be there from the overwhelming majority of other NATO states.
Will the political will to start an actual shooting war with the US be there?
I don’t think there’s a practical ability. The European powers can’t project power outside their boarders without the US helping. Especially with an overseas nation like Greenland.
England and France have a few carriers, but that’s about it. Landing troops would be highly vulnerable to US air superiority. US carriers are larger and more numerous than anything Europe can put up. Based on the local geography, those carriers can stay safe from drone range (a benefit Russia does not have on the Black Sea).
But that also assumes the US military is unified to follow orders into an illegal war, and that may not be the case.
But that also assumes the US military is unified to follow orders into an illegal war, and that may not be the case.
Curious about why it would be an illegal war. Unjust, immoral, unprovoked, and unnecessary are not actually what makes a war illegal.
The invasion of Iraq was entirely based on false pretenses and the military was perfectly unified. Compared to that, an open war of conquest is pretty reasonable.
Wars of conquest were made illegal after Hitler invaded Poland.
It’s illegal by international law–UN charter and the ICC both have sections against invading other country’s territory. International law is only as good as anyone is willing to enforce it, which in the case of Iraq, wasn’t very much.
Why would Greenland be different? Iraq was supported by a paper thin excuse of WMDs, and the history of antagonism. The Trump Administration hasn’t done the legwork to even setup a paper thin excuse beyond “they have resources we want”, and there’s no particular history of Greenland invading its own neighbors or even threatening them. In fact, it’s been an important strategic location for the US Navy’s control of the North Atlantic since WWII. Trump hasn’t bothered with even the slightest attempt at this because he’s an idiot.
Does that mean the military will refuse the order? I really have no idea. It’s not something anybody should count on. More likely, you’ll have different units making different decisions. Some outright refusing, others slow walking their orders while appearing to obey, and others eager to do it. However, it’s possible that the military will refuse en masse.
I think the burgeoning protest movements in the US should also be prepared to take direct action against the military. Things like linking hands to block the gates to weapons factories. And to the naysayers of “what are these protests even accomplishing?”, it’s to prepare a mass movement that is capable of doing this sort of thing.