Although President Donald Trump warned Canada on September 1 that he would exclude them from a new trade agreement unless Canada submitted to his demands, it is not clear that the Trump administration has the authority to do so without the approval of Congress. According to Congressional Research Service (CRS) reports, one published in 2017 and another on July 26, 2018, it is likely that congressional approval to make substantive changes to NAFTA would have to be secured by President Trump before the changes could be implemented.