Donald Trump May Be Falling In Love With Greenland. Taxpayers Beware.

When real estate mogul Donald Trump falls in love with a piece of property, things don’t always turn out so well. Now that he’s president and seems to be slowly falling in love with the idea of buying Greenland—or at least talking about it—it’s a good time to look back at the billionaire’s history of marquee transactions to see how this purchase may unfold.

In the past, his objective was fame and money. But as the leader of the United States, this negotiation comes with a much greater amount of gravitas. Military strategy, geopolitical chess and the cultural balancing act of east versus west. But Trump has made one thing abundantly clear from the day he descended the escalator of Trump Tower in Manhattan to declare his run for office: He’s a transactional guy, and his presidency would be no different.

“Other people paint beautifully on canvas or write wonderful poetry,” he wrote in The Art of the Deal. “I like making deals, preferably big deals. That’s how I get my kicks.”

When reports surfaced last week that he’d asked advisors to look into buying what is the world’s biggest island, many assumed it was a bizarre joke. Perhaps the golf-loving president didn’t realize that, being 80% ice-capped, Greenland is not really green at all?

Over the weekend, however, Trump confirmed that he really would consider making an offer, telling reporters, “Essentially, it’s a large real estate deal” and claiming a vague strategic interest.

“This could be a legacy purchase,” Jack O’Donnell, former president and chief operating officer of Trump Plaza Casino in Atlantic City, told CNN yesterday. But unlike Trump’s past glory shots, which were done with bank money, this one would be funded by taxpayers and would qualify as big by anyone’s measure.

So just how successful might it be? It’s not immediately clear what strategic advantages he’s after or how much he might be willing to pay for them. It’s also unclear just who else might be in the bidding, and how well he might do if he has to compete against other interested buyers.

America’s biggest economic adversary, China would clearly relish a foothold in North America and negotiations over trade aren’t exactly going smoothly after more than two years of talks. He’s much closer to Russia, it would seem, but considering his history with President Putin that may not work out so well either.

Then, there is the state of the trade of sovereign land. That market dried up a century ago, but Trump the dealmaker has made a career out of seeking trophy real estate, and while there have been some colossal flops, there have also been some big wins. He’s no stranger to dealing big, and who would know better that the success of a real estate investment almost entirely depends on what you paid for it? He also seems to believe that everything has a price, even countries.

And this one could be a whopper: Considering Harry Truman’s 1946 proposal to buy the island for $100 million, which would be worth $1.4 billion today, didn’t go through, that price seems unlikely. Looking back to another time the U.S. made a big land investment–when it bought Alaska from the Russian Empire for $7.2 million in 1867—we hardly arrive at a realistic number, either. Now that was a deal, since it values the state at $130 million in current dollars or $220 per square mile. That would make Greenland worth around $184 million.

Valuing it like a public company, the Washington Post landed on price tag of $1.7 trillion—swapping gross domestic product for profits and using Amazon’s peak price-to-earnings ratio of 847.

The private real estate market may offer a more realistic starting point, though the untapped value of oil and mineral reserves would carry a premium, if the sellers are shrewd enough to ask for them. And since the property’s current owner, Denmark, and the Greenlandic people it subsidizes, have already said no, chances are they are going to be shrewd about this one.

So take a look at Pebble. One of the largest privately owned islands in the world is

currently on the market for $1.33 million. Just 41 square miles, the island is orders of magnitude smaller than Greenland’s 836,330. But as part of the Falkland Islands near the South Pole it’s a pretty good comp. Pebble’s $32,000-a-square-mile list price, would make Greenland worth about $27 billion.

Which brings us back to assessing his chances of success.

In 1995, Trump acquired a ground lease on 40 Wall Street, a Manhattan office tower across the street from the New York Stock Exchange. The 72-story building was the perfect feather in an ambitious real estate developer’s cap: landmarked, with a distinctive green roof, the building was constructed to be the tallest in the world. Importantly for Trump, who was still clawing his way back from his first Atlantic City bankruptcy, 40 Wall was also dirt cheap.

Plagued by a connection to Philippines’ authoritarian dictator Ferdinand Marcos, the building had been vacant for years. The president has claimed to have paid just $1 million for the ground lease, which runs through 2059. The actual purchase price was likely a bit higher, but it makes little difference. The building threw off $21 million in net income last year, and Forbes estimates it’s worth $338 million net of debt.

His short-lived ownership of the Plaza Hotel, however, is a very different story. Located just blocks from his beloved Trump Tower, he could see the hotel from his window and became obsessed with owning it.

In 1988 he agreed to pay $407.5 million. The iconic building was well-located on Central Park but in need of major renovations. Trump didn’t care, saying at the time that he was in “in love.” Seven years later, the Plaza had declared bankruptcy and was sold for $83 million less than Trump had paid.

“I think most New Yorkers were horrified at the thought of Donald Trump owning the Plaza thinking that he would glitz it up in his style and ruin that iconic building,” O’Donnell told CNN. “The more he heard that, the more he wanted it, and ultimately because of that, it wound up paying twice as much as the property was valued, and it went into bankruptcy after he bought it.”

This post first appeared on Forbes.com. To see the original, click here.