Canada secured a 30-day postponement in the application of U.S. tariffs on its exports just hours before they were scheduled to go into effect after a call between Prime Minister Justin Trudeau of Canada and President Donald J. Trump late Monday afternoon yielded a border deal that seemed to satisfy both sides.

Mr. Trudeau had earlier pledged to retaliate against U.S. tariffs by imposing tariffs against U.S. goods, too. In the end, he seemed to make modest concessions to Mr. Trump on the border policies, including having 10,000 “frontline’” personnel stationed at the border.

“I just had a good call with President Trump,” Mr. Trudeau said in a social media post and laid out the terms of the agreement. “Proposed tariffs will be paused for at least 30 days while we work together.”

The deal brought relief and de-escalation into what had turned into a brewing trade war between the two close allies and top trading partners, although its 30-day horizon did indicate that more negotiations could take place down the line.

Specifically, Mr. Trudeau said that Canada would create a new position for a Fentanyl czar and redouble its efforts to tackle the opioid crisis — one that kills Canadians daily — by listing cartels and gangs as terrorist entities, like Mr. Trump has said he wants to do in the United States.

He also said that Canada would commit 200 million Canadian dollars to fresh intelligence-gathering efforts around the fentanyl and drug trade.

Mr. Trudeau also said that as part of the agreement with Mr. Trump, Canada would continue to implement a new border-tightening plan it had already announced weeks earlier.

That involves the expenditure of $1.3 billion Canadian dollars in fresh funds over the next several years, the deployment of new technology at the borders and the deployment of more border guards. Canada last month deployed two Blackhawk helicopters and 60 US-made drones to the border to increase surveillance.