Denmark said on Friday it meant seriously that Greenland is not for sale, after Secretary of State Marco Rubio said U.S. President Donald Trump's interest in acquiring the island was "not a joke".

Secretary of State Marco Rubio defended President Donald Trump's interest in acquiring Greenland and gaining control over the Panama Canal, deeming it crucial for U.S. national security interests. During an appearance on SiriusXM's "The Megyn Kelly Show,

"This is in our national interest and it needs to be solved," Rubio said. Greenland's prime minister has repeatedly said the island is not for sale.