About fivernyears ago, a friend from Mexico who studies how marketing experts manipulaternconsumer habits put on a slideshow made up of symbols, and then asked me whatrnword popped into my head with each image. 

There was onernsymbol — which was actually a popular brand name — that conjured up the wordrn“success.” For Mexicans in particular, this brand was gold-plated and generatedrnpositive feelings of accomplishment, power, and respect.   

The brandrnname? “Trump.” 

For ourrnneighbors south of the border, those days are gone. The last time U.S.-Mexicornrelations were this bad, U.S. troops were marching south. 

The notoriousrn19th century invasion and land grab that history records as the U.S.-Mexican War resulted in Mexico losing nearly half its territory. One memorable story involves the Niños Héroes, six teenaged military cadets who fought bravely to their deaths instead of surrendering to U.S. troops during the Battle of Chapultepec Castle. One cadet wrapped himself in the Mexican flag and leapt to his death. The war ended when the neighboring countries exchanged ratifications of the Treaty of Guadalupe Hidalgo in 1848.

Now, seven decades later in 2018, President Trump seems to be spoiling for a rematch.

It is as ifrnTrump has some sort of deep psychological hang-up with our Southern neighbor.rnHe doesn’t belong in the White House. He belongs on a couch.

Thosernsuffering the brunt of his psychosis include Mexicans in Mexico, Mexicanrnmigrants in the United States, and Mexican-Americans who have lived here forrngenerations. 

I havernfriends in all three tribes. 

Consider therntrauma of Mexican-Americans. You might think that most of these folks wouldn’trnhave much of a problem with Trump’s attacks on Mexico and Mexicans because theyrnare often far removed — by time, distance, assimilation — from the lives ofrntheir Mexican ancestors. 

After all,rnMexico betrayed our parents and grandparents. If Mother Mexico had providedrnsufficient opportunity for its children, they wouldn’t have had to run awayrnfrom home and start families of their own north of the border.rnMexican-Americans have the right to hold a grudge against the homeland.

Yet manyrnMexican-Americans are offended by Trump’s anti-Mexico tantrums. They tell mernthat, when he talks in a demeaning way about Mexican immigrants, they feel asrnif he could be talking about their own parents and grandparents. 

First, theyrnwere told — by the most anti-Mexican president since Dwight Eisenhower,rnwho loaded Mexicans onto railroad cars during Operation Wetback in 1954 —rnthat Americans need a “big beautiful wall” on the border to keep outrnMexicans because they're criminals and rapists, that they and theirrnancestors were far from “the best” that Mexico has to offer, and that thernsystem of admitting legal immigrants to the U.S. must be revamped so thatrnfuture arrivals come with more education and skills.

Whether thernissue is drugs, trade, immigration or national security, Trump never passes uprna chance to insult Mexico. 

Now he hasrnresorted to blackmail. Issues that have nothing to do with one another getrnmixed together. If Mexico wants the North America Free Trade Agreement (NAFTA)rnt continue, the president warns, it must stop the flow of drugs and immigrantsrninto the United States.

You wouldrnthink that someone who never tires of telling people how he is “really smart”rnwould grasp the law of supply and demand. Mexico supplies what the UnitedrnStates demands.  

Trump’srntantrums are no way to treat a reliable friend and trusted ally. Mexico isn’trnjust the United States’ No. 2 trading partner after Canada. It’s also a keyrnally in the war on terror, regularly passing along vital information that helpsrnU.S. authorities thwart attacks and keep the homeland safe. 

Recently, DonaldrnTrump tweeted about a “caravan” of migrants coming from Central America throughrnMexico and headed toward the United States. On April 3, Trump warned Mexicanrnofficials — in a tone usually reserved for parents disciplining teenagers —rnthat the caravan “…had better be stopped before it gets there.” Two days later,rnonce the caravan had splintered, Trump tweeted: “The Caravan is largely brokenrnup thanks to the strong immigration laws of Mexico and their willingness to usernthem so as not to cause a giant scene at our Border…”

The presidentrnis the one making a scene — and, in the process, destroying one of our mostrnvaluable relationships.

A president’srnfirst responsibility isn’t to chart a course for the future but to not repeatrnthe mistakes of the past. The escalation of insults, tensions, andrnprovocations that led to the U.S.-Mexican War was a dark and dead-end road.rnAmericans should not travel it again. 

Ruben Navarrette, a contributing editor to Angelus News, is a syndicated columnist with The Washington Post Writers Group, a member of the USA Today Board of Contributors, a Daily Beast columnist, author of “A Darker Shade of Crimson: Odyssey of a Harvard Chicano” and host of the podcast “Navarrette Nation.”