Complex sentence: The leaders of Canada and Mexico have indicated their willingness to work with the Trump administration, and although vague on the exact terms that he will be seeking in a renegotiated NAFTA, Trump has threatened to withdraw from it if negotiations fail.
Split into simpler sentences: The leaders of Canada and Mexico have indicated their willingness to work with the Trump administration. Although vague on the exact terms that he will be seeking in a renegotiated NAFTA, Trump has threatened to withdraw from it if negotiations fail.