Disruption was felt in all three countries, especially Mexico.
Raising the automotive content thresholds and forcing automakers to verify the North American origin of more electronics and other parts now sourced from Asia would cause some parts manufacturers to forego NAFTA benefits, said Ann Wilson, the association's head of government affairs.
Blowing up the deal appears to be Trump's favored choice.
"My optimism toward NAFTA, toward a renegotiation, isn't based on personality or reading political tea leaves", Trudeau said following his talks with Trump.
"I hope the Trump Administration realizes that negotiating without foresight doesn't just adversely affect our economy, it is a return to a panicked approach to globalization and adversely affects the jobs of the 21 Century workforce that depend heavily on American ingenuity".
Phil Levy, senior fellow at the Chicago Council on Global Affairs, pegs the chance of NAFTA's survival at less than 50 percent.
The end of NAFTA would send economic tremors across the continent. In theory, a NAFTA-less North America would revert to the old tariffs, some relatively low (but not for farm products).
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A White House spokeswoman did not immediately respond to CNBC's request for additional information about the president's comments. And no, that stock market rally did not reduce or offset the national debt either. "But we're very honored by it".
In this scenario, the short term consequences for Canada would be severe despite the original Canada-United States Free Trade Agreement remaining in place.
Other U.S. proposals opposed by Canada, Mexico and U.S. business interests include the five-year sunset provision, radical changes to NAFTA's dispute arbitration systems, changes to intellectual property provisions and new protections for U.S. seasonal produce growers.
Trump has maintained his threat to walk out on the fourth round of talks to update the North American Free Trade Agreement, even amid rising opposition at home to his hard-line stance. But U.S. Trade Rep. Robert Lighthizer declared at the outset that the U.S. wouldn't be satisfied with anything but a major overhaul.
The move comes after U.S. aircraft maker Boeing complained that its Canadian rival had received over $3 billion in subsidies from the Canadian federal government and the Quebec provincial government combined.
Those proposals are considered poison pills by Canada and Mexico.
Trudeau defended Canada's limits on dairy imports, according to a lawmaker present in the meeting, saying the prime minister countered by pointing out the US has plenty of support programs propping up its own farmers. But he acknowledged that "we have to be ready for anything and we are". Asked if Nafta is dead, Trump said, "We'll see what happens". But Congress can fight back. Lawmakers could pass a resolution calling on the president to obtain congressional authority before invoking the NAFTA clause that lets countries pull out. They could also threaten to block the president's agenda unless he secures congressional approval to withdraw.
With the clock ticking down towards Brexit day in 2019, British ministers are exploring the options if the world's fifth largest economy drops out of the European Union without a clear trade deal. Some of the tariffs wouldn't be especially high.