What did Donald Trump do today?

He gave himself yet another new tariff threat to back down from.

One day after Trump insisted that he had signed a "deal" with China that nobody in his administration—or the Chinese government—seemed to know about, Trump announced that he was "terminating" trade negotiations with Canada. The supposed trigger was a 3% tax on certain media and technology platforms' business in Canada that has been in the works for three years.

Canada's government responded by, in effect, calling Trump a liar. Prime Minister Mark Carney implied that he didn't expect any actual negotiations to stop over a new trade agreement, Trump's comments notwithstanding. This is increasingly the tack that other world leaders are taking with Trump on trade, refusing to sign more than token and non-binding deals while waiting for Trump to inevitably "chicken out."

At this point, it is almost impossible to keep track of what taxes Trump has hinted at, threatened, imposed, revoked, or head-faked towards. This latest threat would be at least the sixth tariff regime Trump has said he'll impose on American consumers of Canadian goods in as many month, though relatively little of that has actually gone into effect.

In an Oval Office event today, Trump tried to suggest that these threats would force the United States' largest trading partner to accept his terms, even though the previous ones hadn't. "We have all the cards. Every single one. We don't want to do anything bad, but economically we have such power over Canada," he told reporters. "It's not going to work out well for Canada."

In fact, as Trump still seems unwilling to believe or admit, tariffs imposed by the United States are and have always been taxes on American consumers. In the case of goods where Canada is a major supplier to U.S. consumers because the American market isn't big enough to supply everyone, those taxes are compounded by demand driving up the price even further. 

Canada is a major supplier to American consumers for lumber, oil and gas, auto parts, iron, gypsum (used in construction), potash (a component in fertilizer), and many other essentials. Even before today's outburst, state and local officials—including Republican governors—were sounding the alarm about the disastrous effects of imposing barriers to trade that flowed freely and without tax in both directions at the start of the year. There are also strong indications that Canadians angry at Trump's policies are tanking the American tourism industry.

Trump is right about one thing, though—the "cards" he has are enough to do serious damage to the Canadian economy, if not nearly as much in absolute terms as he'd be hurting the United States. It's not clear why he thinks this would be a good thing.

Why does this matter?

• One way to avoid getting a reputation as a cheap bluffer who folds at the slightest resistance is not to keep making cheap bluffs.

• Americans' economic security is more important than Donald Trump's need to feel like a tough guy. 

• The United States literally cannot afford this level of incompetence.