Americans could face shortages of toilet roll and panic buying in supermarkets not seen since the first, nervy days of the pandemic, according to soft but strong warnings from timber and pulp experts.

President Trump’s planned tariffs on Canadian imports, including 27 percent levies on lumber, would raise the price of a type of wood pulp that is a key ingredient in American toilet paper.

“Some of the big branded products not only want softwood pulp from Canada, they want softwood pulp from this particular mill,” said Brian McClay, whose company, BMA, tracks the global pulp market. “They’ve been using it for 30 years and they will not change,” he told Bloomberg.

Pulp is made from the wood chips of sawmills. But if saw mills shut down because of tariffs on Canadian lumber, so would pulp production. This, in turn, would hit American lavatory paper manufacturers.

“If Canadian pulp mills close because they don’t have the fiber supply, I can’t think of any other option for them,” McClay said. “They just can’t switch the recipe around.”

The United States also imports about 10 percent of its toilet roll, about half of which comes from Canada, according to Dino Bianco, chief executive of Kruger Products, Canada’s largest toilet paper producer.

“If you have a supply disruption or unavailability because of tariffs in the US, you’ll have empty shelves and it will be front-page news,” Bianco told the Globe and Mail. Shortages could quickly expose cracks in the social order, he said. “If you can’t buy it at your local Walmart or Costco, you’re going to be screaming at the government.”

Bianco had been attempting to “help governments understand this is a very constrained supply chain,” he said at the time. “I’m not trying to panic people. The market works very efficiently, but the market is so tight that there’s no room to absorb a hiccup of any kind. It would be felt immediately, and there’s no buffer.”

As relations between the US and Canada have soured, not every Canadian has espoused the same delicate approach. Doug Saunders, a columnist at the Globe and Mail, has said that Canada should use its position as pulp and paper supplier as a potent weapon in the looming trade war.

“It would be shockingly easy to empty America’s store shelves of toilet paper,” he said. This had been proven by the pandemic, he wrote. “All it might take to TP-bomb the Americans back to the corn-cob age would be the prime minister, or one of the big-province premiers, seriously mooting the idea of a product-specific embargo on the US airwaves.”

This, he said, would show Americans that Canada knew how to hit them “where it really hurts”.

Will Pavia is the New York correspondent for The Times of London