Donald Trump has warned he will impose a 25% tariff on several European countries until the US is allowed to buy Greenland, the autonomous Danish territory. On Saturday, Trump posted on Truth Social that a 10% tariff will begin on February 1 on goods from Denmark, Norway, Sweden, France, Germany, the UK, the Netherlands, and Finland sent to the US. This tariff will increase to 25% on June 1. Trump said, "This Tariff will be due and payable until such time as a Deal is reached for the Complete and Total purchase of Greenland." The president claims Greenland's current status is a national security threat to the US, though Denmark and other allies dispute this. He also suggested European countries have sent troops to Greenland for unknown reasons, referencing NATO allies deploying forces there after his threat. He claimed incorrectly that Greenland's residents "currently have two dogsleds as protection" and warned that "China and Russia want Greenland," which he called "a sacred piece of land." Trump's tariff threat reverses previous trade agreements, including a pact with the UK announced eight months ago and one with the EU six months ago. He had said the UK would be protected from US tariffs "because I like them." The sudden tariff threat challenges US relations with key European partners. UK political leaders quickly condemned Trump's move. Trump defended his stance, saying, "These Countries, who are playing this very dangerous game, have put a level of risk in play that is not tenable or sustainable." He called for "strong measures" to protect global peace and security. Trump’s use of tariffs as leverage has been common, with some success, including pressuring Colombia to accept deported migrants. He emphasized that the US is "immediately open to negotiation" with Denmark and the other affected countries. Experts fear the tariffs could harm the US economy. Despite signs of strain, Americans face the highest average tariff rate since 1935. The Danish Prime Minister noted that Greenland’s defense is a "common concern" for NATO. European troops are in Greenland to explore Arctic security and reassure the US. A Reuters/Ipsos poll found fewer than 20% of Americans approve of Trump’s Greenland effort, with bipartisan opposition and only 4% supporting military force to acquire it. Meanwhile, the US Supreme Court is set to review the legality of many of Trump’s tariffs, with a decision expected soon.