President Donald Trump showed no sign of backing away from his demand on Wednesday ahead of White House officials' meeting with diplomats from Denmark and Greenland.

WASHINGTON, Jan 14 (Reuters) - Just 17% of Americans approve of President Donald Trump's efforts to acquire Greenland, and substantial majorities of Democrats and Republicans oppose using military force to annex the island, a Reuters/Ipsos poll found.

A Republican congressman from Florida introduced a bill Monday to annex Greenland and make it the 51st U.S. state as President Trump threatens to seize the autonomous Danish territory.

The treaty that created NATO did not contemplate an attack by one ally on another. A seizure of Greenland by President Trump would test the endurance of the mutual-defense pact.

It is the strongest statement by a leader of the Danish territory since US President Donald Trump renewed plans to annex it.

U.S. President Donald Trump said anything less than Greenland "in the hands" of the United States was "unacceptable", reiterating his demand for control of the Danish territory just hours ahead of a White House meeting on the issue.

Greenland’s prime minister said he was trying to end a "geopolitical crisis" by declaring Greenland wants to be part of Denmark, not the U.S.

The United States operated a number of bases in Greenland during the Cold War, which an expert said it could reopen.

The estimate is part of planning around Trump’s efforts to bring Greenland into the U.S. fold, with Secretary of State Marco Rubio tasked with crafting a proposal to purchase the Danish territory.