The Paris Agreement can only enter into force if at least 55 countries representing at least 55% of global emissions have formally acceded to it. This was done on October 5, 2016 and the agreement entered into force 30 days later on November 4, 2016. On June 1, 2017, U.S. President Donald Trump announced that the United States would withdraw from the agreement.  Pursuant to Article 28, the agreement that entered into force in the United States on November 4, 2016 is the earliest possible date for the effective withdrawal of the United States on November 4, 2020. If it had decided to withdraw by leaving the UNFCCC, it could be immediately denounced (the UNFCCC entered into force for the United States in 1994) and enter into force a year later. . . .