by Cokie Roberts and Steven V. Roberts

Here’s a sampling of recent headlines describing President Trump’s pugnacious trade policies. Washington Post: “Trump Thinks He’s Saving Trade. The Rest of the World Thinks He’s Blowing It Up.” Wall Street Journal: “Wider Tariffs Threaten to Take a Big Economic Toll.” New York Times: “America Declares War on Its Friends.”

Trump is fighting his trade war on many fronts: imposing tariffs on steel and aluminum imports; proposing levies on autos from Europe and industrial products from China; threatening to end NAFTA. This all amounts to a very risky game with potentially disastrous consequences — not just for American prosperity, but for the country’s diplomatic and military interests as well.

The president is jeopardizing relations with key allies and displaying a profound ignorance of the postwar international order that’s built on mutual benefit, not unilateral selfishness; on broad alliances, not narrow nationalism.

One measure of the president’s recklessness came after the finance ministers of the G-7, the world’s most industrialized countries, met recently in western Canada. Six of the seven ministers, minus the U.S., issued a stunning rebuke to Trumpism, expressing their “unanimous concern and disappointment” with American trade policies. and warning that “collaboration and cooperation has been put at risk by (U.S.) trade actions against other members.”

Jennifer Hillman, a former U.S. trade official who now teaches at Georgetown Law, was even blunter in the Post: “Trump’s actions create a feeling of chaos and lawlessness. America is no longer abiding by basic due process and commitments made to other nations.”

Trump’s historical illiteracy extends back to the Depression and the calamitous effects of punitive tariffs known as Smoot-Hawley. Chrystia Freeland, Canada’s foreign minister, emphasized the perils of the president’s obtuseness when she told CNN: “We know that beggar-thy-neighbor policies don’t work. That was the lesson of the 1920s and the 1930s. And I really hope people will take some time to reflect on the lessons of history and not go down that path again.”

More than 1,100 economists echoed Freeland’s alarm in a letter organized by the National Taxpayers Union. “Economists are pretty united in their opposition to protectionist trade policy,” Union spokesman Bryan Riley explained to Bloomberg. “It’s the economic equivalent of flat-earth trade policy.”

Even Republicans generally intimidated by Trump are increasingly alarmed at his abandonment of the party’s pro-trade traditions. “There’s quite a bit of resistance to the tariffs,” said Sen. John Cornyn, the second-ranking Republican. “This is an unguided missile, and the retaliation can occur in sectors that are vulnerable.”

Research firm Oxford Economics estimates that steel and aluminum tariffs would preserve 10,000 jobs while costing 80,000. The reason: Companies using higher-priced metal components would have to charge more for products ranging from automobiles to beer cans.

Every economist surveyed by the Wall Street Journal warned that if Trump’s policies triggered “tit-for-tat retaliation” by U.S. trading partners, many more jobs would be lost, with their predictions averaging to 845,000.

The potential damage to U.S. interests goes far beyond jobs lost, however. National credibility is at stake as well. Trump justifies the imposition of steel and aluminum tariffs on national security grounds, but everyone knows that’s a fabricated facade. Canadian Prime Minister Justin Trudeau called out the president’s deception.

“The idea that we are somehow a national security threat to the United States is quite frankly insulting and unacceptable,” he told NBC.

Trump might think his approach of blustery bullying is a smart negotiating tactic, and maybe it worked with New York real estate developers, but even traditional allies like Trudeau must pay attention to their own constituencies and national interests. They cannot knuckle under to American pressure and look weak back home.

But Trump clearly fails to understand that. His philosophy of “winning” means others are losing, and international negotiations simply cannot work that way.

Trump’s strategy “will have an economic bite” and the scars “will last a long time,” said Adam Posen of the Peterson Institute for International Economics to the Post. Those scars will damage not just America’s economic performance but its long-term reputation as a reliable trading partner. “It will be hard to establish trust in the U.S. again, and all the uncertainty will drive down investment and productivity,” said Posen.

International leaders are learning what members of Congress already know: Trump is a mercurial and mendacious negotiator, full of tirades and tantrums, who does not keep his word. Instead of making America great again, he is squandering the trust and good will other presidents from both parties have spent generations establishing.

Steve and Cokie Roberts can be contacted at stevecokie@gmail.com.