LONDON - Despite Denmark's repeated insistence that Greenland is not for sale, U.S. President Donald Trump and his team are "talking ‍about what a potential purchase would look ‍like", according to a White House spokeswoman this week.

But even as a thought experiment that assumes the presence of a willing seller, discussion of the hypothetical sale of ​an autonomous territory such as Greenland rapidly encounters imponderables such as how a meaningful price tag could even be established.

"There's not a market for buying and selling countries," said Nick Kounis, chief economist of Dutch ABN AMRO bank, noting there ⁠was no accepted framework for valuing countries.

Attempts to find historical benchmarks for fair value also run into difficulties.

In 1946 the U.S. offered to buy the vast, mineral-rich Arctic island from Denmark for $100 million - an offer ⁠that ‌was rejected back then.

In today's money, that is around $1.6 billion. But that figure, already paltry, is of no use as a baseline because of the massive growth in both U.S. and Danish economies over eight decades since then: it does not reflect any relative "value" of Greenland and its resources in the global economy of the 2020s.

America's $15-million purchase of Louisiana ⁠in 1803 and $7.2-million acquisition of Alaska from Russia in 1867 are also not useful precedents.

First and most obviously there is the fact that both France and Russia actually chose to sell.

And while it is clear that those figures would be vastly higher in today's money, how much more would depend on how and whether you factored in variables like inflation, appreciation in land prices and growth in local economies.

WHAT IF IT WERE A COMPANY?

So how about if you tried a method akin to the valuation of a corporate takeover based on the income the target is ⁠capable of generating? Still tricky.

Denmark's central bank put the size of ​Greenland's fishing-based Gross Domestic Product (GDP) at a tiny $3.6 billion in 2023 - about a tenth that of its smaller Arctic neighbour Iceland. Even if that was a starting point for a valuation, what multiple would you use to determine a price based on that?

How ‍too would you account for the fact that Danish subsidies cover about half Greenland's public budget, funding hospitals and schools and underpinning infrastructure for the sparsely populated territory?

While Trump has denied the U.S. has its eyes on Greenland's mineral assets and energy assets, Reuters ​reported last October that his administration has held discussions about taking a stake in Critical Metals Corp, a company aiming to build the largest rare earths project there.

Estimates put the value of Greenland's mineral and energy reserves in the hundreds of billions of dollars or more. Proper geological studies of the entire island have not been fully conducted but a 2023 survey showed that 25 of 34 minerals deemed "critical raw materials" by the European Commission were there.

Mining and energy companies have a long history of putting price tags on assets around the world. But here, at least two complications emerge.

First, the extraction of oil and natural gas is banned in Greenland for environmental reasons, and development of its mining sector has been snarled in red tape and opposition from Indigenous people. Is that a political constraint that a buyer would want a discount for? If so, how much?

And second, mining and energy deals crucially do not include the transfer of national sovereignty - in this case complicated further by the presence of Greenlandic Inuits who assert ownership claims of their own.

"Because you are adding the intangible notions of Indigenous peoples' culture, history, then you can't - there is no way to price it," said Andreas Osthagen, Research Director for Arctic and Ocean ⁠Politics at the Fridtjof Nansen Institute in Norway. "It's why that notion is ridiculous."

For now, the Trump administration says all options ‌are on the table - including military action - to gain control of a territory that it says is vital for U.S. national security and where it already has a small military presence.

U.S. Secretary of State Marco Rubio's scheduled meeting with Danish leaders next week may yield further insights into the U.S. game plan on Greenland.

ABN AMRO's Kounis suggested Trump could be using a similar playbook to one he has used in other ‌situations such as talks ⁠on trade tariffs, where an extreme scenario is put on the table simply to soften up the other side.

If one possible outcome is an agreed settlement that the U.S. sees as being to its military and ⁠economic advantage, then "part of this might well be about getting leverage for future negotiations", Kounis said.

(Additional reporting by Ernest Scheyder in Houston Editing by Frances Kerry)