When Ronald Reagan delivered one of the most stirring speeches of his presidency in Normandy on the 40th anniversary of D-Day, he hailed “the boys of Pointe du Hoc,” the Army Rangers, who, despite gruesome casualties, scaled the cliffs on Omaha Beach.

That June 6, 1984, speech, written by Peggy Noonan, also took pains to credit “the unsurpassed courage of the Canadians who … once they hit Juno Beach, they never looked back.” Of the 14,000 Canadian troops who landed on D-Day, more than 1,000 died in the first six days of the invasion.

Reagan understood, as all modern American presidents did prior to Donald Trump, that D-Day commemorated the shared sacrifice of Americans and our Canadian and British allies. This crusade was not “Make America Great Again” — and certainly not “America First” — but rather “Make the World Safe from Tyranny and Genocide.”

In normal times, this week’s G7 summit at the majestic Fairmont Le Manoir Richelieu Hotel in Charlevoix, Quebec, would be a moment to reaffirm our bonds with our allies. Looking from the hotel across the broad expanse of the St. Lawrence River, it is hard not to reflect on the shared American-Canadian experience in settling a vast continent over more than four centuries.

Instead, the dominant theme at the G7 will be the stiff tariffs on steel (25 percent) and aluminum (10 percent) that Trump unilaterally imposed last week on imports from Canada, Mexico and the European Union. Trump’s major target is Canada, which is the largest exporter of steel and aluminum to the United States.

Against party interests

Trump’s eagerness to embark on a global trade war not only jeopardizes the booming American economy, but also runs counter to both the short- and long-term interests of the Republican Party.

Don’t just take my word for it. Read last week’s unequivocal judgment from the conservative editorial page of the Wall Street Journal: “So much for Donald Trump as genius deal-maker. We are supposed to believe his tariff threats are a clever negotiation strategy, but on Thursday he revealed he’s merely an old-fashioned protectionist. His decision to slap tariffs on steel and aluminum imports from Europe, Canada and Mexico will hurt the U.S. economy, his own foreign policy and perhaps Republicans in November.”

A new survey of major CEOs by the Business Roundtable found that 95 percent of the corporate chieftains believe “foreign trade retaliation leading to lower U.S. exports” was a moderate or serious risk to the economy.

Charles and David Koch — the billionaire brothers whose lavish spending helped create Republican congressional majorities — have decisively broken with the Trump administration on trade. Even as David Koch steps aside for health reasons, Koch-funded organizations like Americans for Prosperity have announced a multiyear political drive to promote free trade.

Even by Trump standards, that is an impressive array of self-inflicted wounds. To lose the Wall Street Journal editorial page, the nation’s CEOs and the Koch brothers with one impulsive gesture represents a level of political ineptitude unmatched since GOP leaders like Reince Priebus naively believed they could tame the 45th president.

And Trump was warned.

At White House meetings, virtually every Republican senator from the Midwest cautioned about interfering with business supply chains with Canada. Others warned about retaliatory tariffs against agricultural exports.

Put another way, five potentially vulnerable Democratic senators on the ballot in 2018 represent states that neighbor Canada: Jon Tester (Montana), Heidi Heitkamp (North Dakota), Tina Smith (Minnesota), Tammy Baldwin (Wisconsin) and Debbie Stabenow (Michigan). It is a safe bet that the Trump tariffs and their ramifications will be highlighted in Democratic campaign ads.

ICYMI: Rubio Leads Chorus of Lawmakers Critical of Trump’s Trade Talks With China

The reaction of congressional Republicans to the tariffs was sadly predictable — hand-wringing devoid of effective follow-up.

Typical was the response of Paul Ryan: “I disagree with this decision. Instead of addressing the real problems in the international trade of these products, today’s action targets America’s allies when we should be working with them to address the unfair trading practices of countries like China.”

But even though Congress, in theory, controls trade policy, there appears to be limited appetite on Capitol Hill to actually do anything other than gin up press releases and tweets. Mitch McConnell made clear Tuesday that he would not bring to the floor a stand-alone bill to overturn the Trump tariffs.

Amid the nonstop distractions of Trump’s chaos presidency, it is difficult to separate the lasting from the ephemeral. That’s why last week’s tariff announcement was quickly trumped on cable TV by everything from the president’s no-law-can-touch-me tweets to the disinviting of the Philadelphia Eagles to the White House.

The rules governing international trade are — let’s be honest here — less riveting than arguing over Samantha Bee and Roseanne Barr.

Loyalty test

But Trump’s trigger-happy enthusiasm for trade wars may test the lapdog loyalty of congressional Republicans like few other issues. Before Trump, free trade was one of the pillars of GOP ideology, along with lower taxes and fewer regulations.

Lockstep Republicans can probably convince themselves, if they watch Fox News long enough, that Trump is somehow the martyr in the Robert Mueller investigation. But it is a much bigger ideological step for these Republicans to suddenly decide that Bernie Sanders and other protectionist Democrats are right on trade while the Wall Street Journal editorial page and the Koch brothers are wrong.

Only Trump — with his blithering understanding of economics, alliances and international negotiations — could manage to launch a trade war with Canada on the eve of the 74th anniversary of D-Day and the G7 summit in Quebec.