The implementation of the steel and aluminum tariffs announced by President Donald Trump last week Thursday could signal a harder line by the White House on other trade issues, including leaving the North American Free Trade Agreement, a Goldman Sachs economist said.

“The potential announcement of steel tariffs could alleviate political pressure on the White House to pursue other trade restrictions in the near-term, but they also suggest to us a rising probability of trade-restrictive outcomes to other pending issues,” wrote Alec Phillips, in a note Thursday afternoon.

Last week, Trump announced he would slap tariffs of 25% on steel and 10% on aluminum imports next week. This “would be the most substantial trade restriction the administration has announce to date,” Phillips said.

“We expect further disruptive trade developments over the coming months, including stalled Nafta negotiations and potential restrictions on Chinese trade and investment,” he wrote, especially as the new tariffs also concern U.S. allies.

On Monday, Trump tweeted, linking the new tariffs to Nafta and fuelling worries about impending trade wars.

Read:EU considers retaliatory tariffs on $3.5 billion U.S. imports: report

Also see:Trump steel tariffs to hit these 8 countries the hardest—and China isn’t one of them

Round seven of the Nafta talk are currently under way in Mexico City — with no immediate end in sight. This round is set to conclude on Tuesday. And a U.S. administration reassured in its protectionist stance on trade, could imply a rougher opponent at the negotiating table.

“There is a good chance that this could eventually lead the president to announce he intends to withdraw from Nafta,” despite expected near-term successes on smaller technicalities, the Goldman note said. However, a U.S. exit from the trade pact wasn’t likely in the short-term.

The U.S. is also investigating China’s intellectual property and technology transfer practices, and Goldman expects “that the administration will ultimately announce restrictions on investment by Chinese companies in the U.S.”

Read:Here’s why the Dow is taking the Trump tariffs so hard

Stocks tumbled after the announcement Thursday and opened sharply lower on Friday, before trimming losses, with the S&P 500 SPX, -2.11% briefly trading higher in choppy trade. In recent action, the S&P 500 was off 0.2%, while the Dow DJIA, -2.76% was down 178 points, or 0.7%.

Last week’s metals tariffs are different from previous action the Trump administration has taken on trade, as prior ones, such as on solar panel and washing machine imports, weren’t as broad and far-reaching.

Also, “unlike routine anti-dumping and countervailing duty cases or less common safeguard cases, the section 232 authority the president will apparently use [for the metals tariffs] is rarely used and more controversial, as it does not rely on any economic argument and instead imposes trade restrictions on national security grounds.”

Also read:‘No big deal’: Wilbur Ross on the consumer price impact of Trump’s tariffs

The fallout from this could lead to a weakening of international trade conventions, such as the rules of the World Trade Organization, Phillips said.

Still, many questions remain and “the details do not appear to have been finalized so while action seems likely, many aspects of the decision could change over the next week,” he wrote.