A proposed U.S.-Mexico trade deal would allow President Donald Trump to slap punitive tariffs of up to 25 percent on imports of Mexican-made cars, SUVs and auto parts above certain volumes, auto executives and sources said on Tuesday. The United States and Mexico agreed on Monday to overhaul the North American Free Trade Agreement (NAFTA), pressuring Canada to sign up to new auto trade and dispute settlement rules to remain part of the three-way pact. But a previously unreported side agreement between the two countries would allow the United States to pursue "national security" tariffs on annual Mexican car and SUV imports of over 2.4 million vehicles. The side deal would allow national security levies on auto parts imports above a value of $90 billion per year on the same grounds. The administration plans to announce the results of a probe into whether autos and part imports pose a national security risk in the coming weeks