Additionally the economies of the 3 nations are so integrated through the free trade agreements, his demands, had he carried them through would have been extremely costly, to Americans.

This is my conclusion at this time. Then I stumbled across the article below, which summarizes nicely.

Trump got what he wanted with the Canada and Mexico tariff pauses — even if he didn't get that much

US President Donald Trump has just shown the world how the Art of the Deal works.

The tariffs were initially set to take effect on Tuesday. But after an early morning stock market downturn on Monday, talks with Canada and Mexico resulted in a 30-day tariff delay.
In exchange for the pause, Mexico agreed to deploy 10,000 National Guard troops to its northern border to curb illegal activities. Canada agreed to a set of initiatives targeting drug trafficking, money laundering, and border security.

The US is trading off, too

While Trump’s deals with Canada and Mexico may have been swift, the tradeoff is ill will toward the US in both countries and uncertainty in the international trade order.

Yup, the stock market tanked and Trump is generating loads of ill will globally.

“The trade rules are valuable because they create a predictability and certainty for countries and for companies that do business in North America and in the world,” said Edward Alden, a senior fellow at the Council on Foreign Relations. “And to mess with those rules for no good reason is truly irresponsible.”
“He has no evidence to show he is able to use tariffs to achieve significant concessions, economic or otherwise,” he added.
Some experts said the agreements could have been achieved without threatening tariffs.

“Using the issues around fentanyl and illegal immigration to justify a trade war is somewhat bizarre,” said Romel Mostafa, an assistant professor in economics and public policy at the Ivey Business School in Ontario. “It seems like we put the cart before the horse here, which is we basically went into this tariff imposition and counter-tariffs and then came to the discussion table.”
Alden said the agreements are “not in the slightest” a significant concession because the Mexican government has long had an interest in cracking down fentanyl smuggling and better controlling its border. As for Canada, he pointed to data from the US Customs and Border Protection showing that the northern neighbor accounts for just 0.2% of US border fentanyl seizures.

“The bigger question is whether potentially we could come back again a month later and there could be other demands coming in,” Mostafa said of Trump’s actions.

China and Fentanyl

China has said fentanyl is the US’ own problem and that Beijing would challenge the tariffs at the World Trade Organization.

“The US needs to view and solve its own fentanyl issue in an objective and rational way instead of threatening other countries with arbitrary tariff hikes,” a Chinese foreign ministry spokesperson said on Sunday.

I think the US, like Canada, needs to solve it’s fentanyl and opioid issue itself, as well. It’s a domestic issue, needing to be solved within it’s own borders.