Quick passage of the new U.S.-Mexico-Canada Agreement appears to now possibly be in question as Donald Trump threatens to slap a tariff on all Mexican imports, unless the country does more to block the surge of Central American migrants trying to cross into the U.S.

If Mexico cannot stop the flow, Trump promises, as of June 10, to slap a 5% tariff for starters, possibly rising to 25% by October.

”In order not to pay tariffs, if they start rising, companies will leave Mexico, which has taken 30-percent of our auto industry, and come back home to the U.S.A,” Trudeau tweeted.

Wall Street markets plunged with automarkers among those recording losses.

Mexico’s president says his foreign relations secretary will lead a delegation to seek a peaceful, negotiated solution.

Meanwhile, Canada is staying clear of the dispute.

”This border issue between Mexico and the United States is a bilateral issue, just as the border question or the management of our shared border with the United States is bilateral issue between Canada and the United States,” according to Foreign Affairs Minister Chrystia Freeland.

The U.S. recently lifted the tariffs on steel and aluminum from Canada and Mexico, which both countries said stood in the way of ratification of the USMCA all three signed the end of last year.

The agreement does not take effect until it’s approved by the legislatures of the three countries.