If the United States/Trump tries to buy Greenland, doesn't Congress have to approve the funding?

Where will Trump get the money to buy Greenland? I thought Congress is in charge of funds.

I think Congress will not approve any funds since the American people think Trump has totally lost his mind about Greenland and going against our allies.

If the United States/Trump tries to buy Greenland, doesnt Congress have to approve the funding?
If the United States/Trump tries to buy Greenland, doesn't Congress have to approve the funding?
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