It's crazy. U.S. President Trump posted on social media on the 17th, announcing that the United States will impose a 10% tariff on imports from Denmark, Norway, Sweden, France, Germany, the UK, the Netherlands, and Finland starting February 1st.

Trump said that the tariff rate will be increased from 6% to 25% starting June 1st, until the relevant parties reach an agreement on the U.S. "comprehensive and thorough purchase of Greenland." He also stated that the U.S. is open to immediate negotiations with the aforementioned eight European countries.
Trump claimed that the personnel from the eight countries visiting Greenland have "unknown purposes." He warned that these countries "are playing a very dangerous game," raising the risk to an unsustainable critical point. "To protect global peace and security," urgent "strong measures" are needed to quickly change this potentially dangerous situation.