Officials from Greenland and Denmark met in Washington on Wednesday with top White House officials as U.S. President Donald Trump moved to ratchet up the pressure by suggesting that NATO should help the United States acquire the world’s largest island, saying anything less than it being under American control is unacceptable.

As senior officials held talks in Washington, Denmark announced plans to boost the country’s military presence in the Arctic and North Atlantic, as Trump tried to justify his calls for a U.S. takeover of the vast territory by repeatedly claiming that China and Russia have designs on Greenland.

Trump again cited what he says is the threat from Russian and Chinese ships as a reason for the U.S. to take control.

“NATO should be leading the way for us to get it,” he wrote, adding that otherwise Russia or China would — “AND THAT IS NOT GOING TO HAPPEN!”

“NATO becomes far more formidable and effective with Greenland in the hands of the UNITED STATES,” Trump wrote. “Anything less than that is unacceptable.”