Things got heated this morning on CNN, as Rep. Mo Brooks (R–Ala.) and New Day co-host John Berman argued over whether we need a wall on the U.S.–Mexico border. The argument reached its low point when Brooks decided to start invoking 9/11.

"Let's look at 9/11 by way of example," the Alabama Republican said. "We lost 3,000 people, more or less, on 9/11. That justified going to war in Iraq and Afghanistan, and our troops are still there to varying degrees. 3,000. With the southern border, we have the loss of at least 15,000 Americans a year—that's part of the justification." (He seems to have conjured that dubious figure by adding a debatable count of the number of people killed by illegal immigrants in 2017 to the number of people who have overdosed on imported heroin since 1999.)

The 9/11 attacks were indeed used to justify the wars in Afghanistan and Iraq. The U.S. entered Afghanistan in 2001 with the goal of taking down the Taliban, who they accused of giving safe haven to Al Qaeda. That war has cost more than $1 trillion, not to mention the lives of over 2,300 Americans and even more Afghans. Yet according to a government watchdog's report to Congress last year, the violence and instability in the country has only gotten worse. And does anyone really believe that Americans are any safer?

Yuri Gripas/REUTERS/NewscomYuri Gripas/REUTERS/NewscomIn 2003, the U.S. went to war in Iraq, accusing Saddam Hussein of developing illicit weapons of mass destruction. They turned out to be wrong about that. Still, almost 5,000 Americans died as a result of the war. The exact financial cost is murky, but it's at least $800 billion

And Brooks is citing these wars as a precedent? If anything, they're a reason to remember that the response to a tragedy can itself be tragic and ill-advised. America's open-ended wars were a mistake; and it would be a mistake to spend billions of taxpayers' dollars on a border wall that won't even work.