According to two sources on the matter, U.S. officials have ordered spy agencies to step up their efforts to intelligence in Greenland, which is apparently still apparently still focused on the acquisition of the island.

The directive was first reported by the Wall Street Journal.

The move caused objections from Denmark, a NATO ally who ruled the semi-autonomous island.

Denmark's Foreign Minister Lars Løkke Rasmussen said he would call the report of the US ambassador. According to the Ritzzo News Agency, “This is very worried because we don’t monitor our friends.”

Sources said the intelligence director’s office issued a directive to intelligence agencies last week to gather information about Greenland’s independence political movement, views on U.S. interest in island resources and identify people supporting Washington’s targets for the Arctic Island.

Sources said the directive was in the form of “collecting emphasis information” that sets priorities for intelligence work.

"We do not comment on intelligence matters. However, the president is very clear that the United States is concerned about security in Greenland and the Arctic," White House National Security Council spokesman James Hewitt said in an email.

Tulsi Gabbard, director of national intelligence, claimed in a statement that administration officials tried to undermine Trump by leaking confidential information.

"The Wall Street Journal should be ashamed of helping deep state actors who undermine the president by politicizing and leaking confidential information," the statement said. "They are breaking the law and undermining the security and democracy of our country. Those who leak confidential information will be found and responsible to the maximum extent of the law."

"I have turned over three illegal leaks to the Justice Department for criminal prosecution and we are investigating nearly a dozen," Gabbard added.

Marc Polymeropoulos, a former professional CIA official, said it was unclear why the administration gathered information from espionage about diplomats or possible U.S. allies from open source research.

"This seems to be handled through diplomatic and State Council channels," he said. "Why waste valuable intelligence resources?"

In an interview with NBC News's Kristen Welker last weekend, Trump refused to rule out the capture of territory by force.

"I'm not saying I'm going to do this, but I don't rule out anything," Trump said. "We need Greenland a lot. Greenland is a very small number of people, we will take care of, we will cherish them, all of that. But we need to be needed for international security."

"One way or another, we're going to get it," Trump said in a speech at a joint meeting of Congress in March.

A January poll commissioned by Danish newspapers Berlingske and Greenlandic Daily Sermitsiaq shows that 85% of Greenland don’t want their islands to be part of the United States.

The U.S. military has a base in northwest Greenland that is part of the early manufacturing system for ballistic missiles.

Greenland has been increasing its strategic importance as global warming sparks competition from the Arctic among the world's major powers. Greenland is increasingly rare earth minerals, uranium and iron, as climate change can make these natural resources more accessible.