BERLIN, Germany told Donald Trump on Wednesday that borders must not be changed by force after the US president-elect refused to rule out military action to take Greenland, an autonomous territory of Denmark.German government spokesman Steffen Hebestreit said in response to Trump's remarks that "as always, the firm principle applies... that borders must not be moved by force", pointing to international agreements such as the UN Charter.Trump, in a news conference on Tuesday, refused to rule out military intervention over Greenland and the Panama Canal, both of which he has said he wants the United States to control.Trump also called the border with the United States' northern neighbour Canada an "artificially drawn line" and promised to rename the Gulf of Mexico the "Gulf of America".Hebestreit refused to be drawn on whether the German government takes Trump's threats against NATO allies Denmark and Canada seriously."I don't want to assess" the comments, Hebestreit told a regular news conference, adding only that the German government had "taken note" of them.