U.S. President Donald Trump said Monday evening that his recent grievances with NATO trace back to a standoff earlier this year over Greenland.

“It all began with, if you want to know the truth, Greenland,” Trump said during a White House press conference. “We want Greenland. They don’t want to give it to us. And I said, ‘bye, bye.’”

The remark revives a dispute that rattled transatlantic ties in January, when Trump threatened to take control of the self-ruling Danish territory before backing down after an agreement was struck. The episode sparked alarm across Europe, with Denmark reportedly preparing contingency plans in case of a U.S. invasion of the island.

Trump used the Monday press conference to broaden his attack on NATO, accusing transatlantic military allies of failing to support Washington during the Iran war.

“I think it’s a mark on NATO that will never disappear,” he said, adding he was “very disappointed” by the lack of military backing after several countries — including Spain — refused to grant access to bases or airspace, and European governments declined to send warships to secure the Strait of Hormuz.

The comments echo a growing drumbeat of criticism from the Trump administration. Trump floated the idea of pulling the U.S. out of NATO last week, while U.S. Secretary of State Marco Rubio warned the alliance risks becoming “not a very good arrangement” for Washington.

European leaders have so far resisted U.S. pressure. In a call last Thursday involving more than 40 leaders, governments discussed diplomatic and economic steps to reopen the Strait of Hormuz but stopped short of any concrete military commitment. French President Emmanuel Macron went further, warning such a military operation would be “unrealistic.”

NATO Secretary-General Mark Rutte is set to meet Trump, Rubio and U.S. Defense Secretary Pete Hegseth in Washington on Wednesday in a bid to ease tensions.

Trump, for his part, appears unimpressed.

“They’re going to say, ‘oh, we’ll do this. We’ll do that,’” he said. “Now they all of a sudden want to send things.”