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 said during an interview that President Trump’s wish to acquire the Arctic island Greenland is serious and rooted in national security concerns for both the rest of

"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.