As has been commented by others, this problem is solvable with allies. Security in the north Atlantic area isn't just a Denmark concern, it's a concern for a number of countries and one obvious solution is to form a defensive alliance around some sort of treaty. Maybe even a organization...
The reliance on allies is actually the central issue here. It is exactly the notion that European allies lack both will and capability, that drives the US to secure its interests independently.
The entire US security policy regarding Europe is driven by frustration with Europe over their systemic security neglect.
The problem is that the US isn't treating Denmark like an ally, but rather like a satellite state. There is a fundamental difference in kind here. That's the concern.
If you have a strategic interest but all your ally can offer is thoughts and prayers, what do you do?
Well actually if it's not an ally you can just take it by force or will no consideration for them. If it's an ally you can make very good offers like economic or industrial or security incentives.
The world isn't made up of the US, RoK, and Israel. There are many other manufacturers. If there is a reason to move away from depending on the US, there is a market large enough within European NATO to support an alternative.
SK and Israel were listed as non-European suppliers. Internal European MIC is not yet sufficient to fulfill most nations' security demands so outside sources are required.
You can have a healthy defense trade but still move towards minimizing dependence. The real problem is, if the US decides to use force to seize Greenland, will a US dependence compromise the ability of Denmark to resist this?
That is very hypothetical. I do not think Denmark would be well served cutting itself off American arms. I think that would be a major strategic mistake. And by no means would Denmark have any way to resist it if it was really a forceful takeover. So I don't think dependence would even be part of that calculus.
Most realistic outcome is to suck it up.
This is really dishonest and untrue. A simple example is Crimea with Russian bases pre-'14 and annexed Crimea post-'14. There is a huge difference between Greenland being part of the US or part of Denmark with US military bases. There are US military bases in South Korea. Is "ownership" of South Korea "mixed"? Most would say obviously not, though I'm sure you could twist some strange definition into being. And let's not forget the fundamental problem, the USA isn't asking for a bigger presence in Greenland. It's Trump trying to first buy Greenland and then threatening to take it by force. Without or without the support of the local population, and certainly without much regard for the sovereignty of another allegedly allied nation-state.
I'm not making any definitions. I'm saying things in ways I think will be better understood. But I am against hard definitions. I think it's most important to understand some abstract principles here, like assurances.
If the US really had no regard for the sovereignty and friendship of its allies, there'd be no negotiations. Just an instant takeover and that's it.
Consider this realistic scenario:
The US wants to expand facilities in Greenland ahead of an anticipated scenario. It notifies Denmark as per agreement. But this time Denmark objects. Like those around it, foreign influence made it hostile.
Waiting for a new gov't will take too long and time is of the essence. What do?
If Denmark and the USA are allies, then it's ridiculous to expect Denmark to have to negotiate with the USA about getting to keep their own territory. This simply isn't how allies behave. Hence the concern.
Allies do not negotiate? What do allies do then? Start shooting one another?
You can't take an argument I'm making seriously, because some other entity is also making that argument and may be disingenuous? This strikes me as sophistry, a convenient excuse to disregard what you don't like or don't want to face up to.
You made a "colonialism imperialism" argument?
I've always felt this was your belief, but you've always tried to argue that your position was supported by international law. Thank you for coming out openly.
My full system of beliefs on international laws and norms and geopolitics is much better described by "peace through strength", or a careful balance of "might makes right" with international norms.
There must be norms derived from enlightened values, but these norms must be enforced, by military if necessary.
And if these norms become dated to the point they're turned against us by their opponents, then it is time to reform them and start enforcing.
None of them is actually derived from words existing on paper and nations enslaved by these words.
This guy here actually describes my view on this quite well:
A simple logical question might be why a country would voluntarily choose to limit it's policy options by some unenforced constraints from international law. The answer is that if the country is a democracy whose leadership is reasonably faithfully executing the mandate of it's people then they may want their country to abide by said law.
It is usually more closely tied to a sense of morality. There was a lot of whinyism regarding Israel-Gaza when people were claiming Israel violated some international laws and that it was genociding or whatever. And that is just a perversion of the causality. Israeli soldiers didn't shoot random Palestinian civilians not because of some sense of respect for international law. But because you can't really convince one to do it. But if you somehow land on someone you can convince, then he's looking at several years in prison because of local law.
Right now the world is still somewhat unipolar. The US is the dominant superpower. If it becomes bipolar or multipolar, with China and others becoming superpowers, then we can expect the "international law" to splinter because there will be more enforcers but with radically different world views and what is considered acceptable.
The Swords of Iron war started on Oct 7th, involving 7 fronts spanning much of the middle east, embodied the acceptable norms of Iran, its proxies, and other regional terrorist groups. They account for a vast region on this earth. They have their own norms separate from our own. For all purposes, "our" international laws have absolutely no bearing on them. But they actually started increasingly complying with our international laws simply because of a multinational effort to vaporize them.
And vice-versa, Russia might be an authoritarian oligarchy but if* they generally abide by international law and leave their neighbors alone, you can do business with them and potentially even develop a level of trust despite their government.
*This is a hypothetical that obviously isn't actually the case in our world.
When the war ends, given a bit of time, trade will be restored. That's not international law. That's just how the market works. If your stuff is as good but cheaper, people will buy your stuff. And Russia has stuff.