UNITED NATIONS, Sept. 22 (Xinhua) -- The United States, Denmark and its autonomous territory of Greenland on Tuesday signed an agreement in New York to expand the U.S. military presence on the strategic Arctic island. At a ceremony on the sidelines of the UN General Debate, the agreement was inked by U.S. President Donald Trump, Danish Prime Minister Mette Frederiksen and Greenland's Prime Minister Jens-Frederik