President Donald Trump's threat to raise tariffs on Mexican auto exports came a day after he said he would give the country one year to crack down on illegal border crossings. | Chip Somodevilla/Getty Images Trade Trump says Mexico auto tariff threat supersedes new NAFTA pact

President Donald Trump said Friday that the deal his administration struck with Mexico on its auto exports won't count if the country fails to stop Central American migrants from illegally crossing the border to enter the United States.

If "for any reason Mexico stops apprehending and bringing the illegals back to where they came from, the U.S. will be forced to Tariff at 25 percent all cars made in Mexico and shipped over the Border to us. If that doesn’t work, which it will, I will close the Border," Trump wrote on Twitter.


"This will supersede USMCA," Trump continued, referring to the new North American trade deal, which has yet to be ratified in the U.S., Mexico or Canada. "Likewise I am looking at an economic penalty for the 500 Billion Dollars in illegal DRUGS that are shipped and smuggled through Mexico and across our Southern Border. Over 100,00 Americans die each year, sooo many families destroyed!"

Trump's threat to raise tariffs on Mexican auto exports came a day after he said he would give the country one year to crack down on illegal border crossings before he brings down the tariff hammer. That represents a retreat from his previous threat to immediately close the border, an action that many industry groups and economists argued would have a catastrophic effect on the U.S. economy.

But the president's remarks Friday morning also raise questions about whether he will abide by the terms of any trade deal he strikes or whether he will continue to insist on more concessions from trading partners after agreements have been reached.

In the final months of talks to renegotiate NAFTA, Canada and Mexico faced the threat of Trump imposing a 25 percent tariff on their automobile and auto parts exports to the United States as a result of a Commerce Department investigation into whether imports of those goods pose a threat to U.S. national security.

Both countries negotiated quotas with the Trump administration that would shield a certain amount of their auto exports from any new duties Trump could impose on national security grounds. In Mexico's case, the U.S. agreed to exclude 2.6 million passenger cars, all light trucks and $108 billion in auto parts trade from any national security tariffs.

That agreement, which came in the form of a side letter to the U.S.-Mexico-Canada Agreement, is already in force, even though none of the three nations have approved the NAFTA replacement.

Trump said on Friday he would not be constrained by the side agreement if he feels Mexico has not done enough to restrict illegal border crossings. But he also indicated he did not expect to have to impose the tariffs on Mexican auto exports, because he believes the United States' southern neighbor is already doing more to help his administration stem the tide of migrants crossing the border illegally.

"Mexico, for the first time in decades, is meaningfully apprehending illegals at THEIR Southern Border, before the long march up to the U.S. This is great and the way it should be. The big flow will stop," Trump said.