Earlier: Israel To Greece: Shoot Muslim “Infiltrators”…In The Knee. It Works.

The Posse Comitatus Act of 1878 is intended to prevent the US Army from being used on Americans. In the anti-terrorist panic after 9/11, various people made noises about suspending it. (One of them was Joe Biden.)

As early as 2006, when Bush was thinking about putting National Guard, rather than Army, troops on the Border, we noted that it's been repeatedly suggested that using the Army for border control would violate the Posse Comitatus Act, designed to prevent the Army from being used on Americans. (E.g. Raoul Lowery Contreras, in the middle of an attack on us here: "It is illegal to put troops on the border.") No, it wouldn't—and it isn't.

Aside from the multiple modern exceptions to the Act, what is at issue here is a matter of guarding the border from foreign invaders. This is, as we've said repeatedly, is what armies are for.

It turns out that the Trump Administration contained—until they betrayed him publicly—two intrepid warriors who believed that the Posse Comitatus Act somehow prevents the American Armed Forces from defending the country from invasion: Generals John Kelly, USMC, retired, and James "Mad Dog" Mattis, USMC, retired.

Here are some excerpts from the book Border Wars: Inside Trump's Assault on Immigration, by Julie Hirschfeld Davis and Michael D. Shear, emphases added:

• Mattis was taken aback, although his dour expression betrayed no emotion. Under a late-nineteenth-century law known as the Posse Comitatus Act, much of the military was barred from performing domestic law enforcement duties, such as policing a border, and the principle had long been seen as sacrosanct.
• ...Kelly tried to explain the limits of what the troops were allowed to do at the border. They could help fortify it with barbed wire and build tent cities to help ease the crunch on ICE and CBP, which were rapidly running out of space to hold migrants. But military personnel couldn’t actually touch a migrant, either to detain one or to provide any kind of care or service. And they certainly could not use force to push them back, Kelly explained. Trump was not hearing him.
• [Trump] talked extensively about the role of the military, and, under questioning by reporters covering his comments, suggested that the troops might use lethal force to confront immigrants at the border. Asked what the American forces would do if migrants threw rocks, Trump answered: “If they want to throw rocks at our military, our military fights back,” the president said. “I told them, ‘Consider it a rifle.’?”
  
  Nielsen and her top aides, who were traveling to New York for meetings and had watched Trump’s remarks on Fox News, were horrified. The president had just suggested, in comments carried live on TV, that American soldiers had license to shoot to kill migrants at the border. Once again, they dropped everything to head off a presidentially created crisis. Nielsen frantically asked her staff to find the CBP use of force policy and send it over to the White House immediately. Someone had to show it to Trump and get him to walk back his comments right away, she said. Kevin McAleenan, the CBP chief, called DHS lawyers to discuss the policy. The rules were very clear. They stated that DHS personnel “may use deadly force only when necessary, that is, when the officer/agent has a reasonable belief that the subject of such force poses an imminent danger of serious physical injury or death to the officer/agent or to another person.” If migrants were throwing rocks, it would have to be met with commensurate nonlethal force—not live ammunition from rifles, as the president had suggested.
  
  Trump appeared to get the message, and he backed off publicly from the idea of the military firing on migrants. When reporters asked him about it the next day, he said rock throwers would be arrested, and responded to a question about whether he could promise that the U.S. military wouldn’t shoot at civilians at the border by saying, “Well, I hope they won’t.” But privately, Trump badly wanted to find a way that they could. A few days later, in a meeting with DHS officials, the president brought up the idea again. Listen, I get it, okay? he told them. If someone throws a rock, you can’t shoot to kill. But would it be okay just to injure them? What if we shoot these migrants in the legs? To slow them down? That’s not lethal force, right? Nielsen and her aides were flabbergasted.No, they responded quickly. That’s not allowed either.

Well, the Israeli experience has shown that it is allowed, and it works. The problem here is that Kelly and Mattis believed the idea that the Posse Comitatus Act applies to the Border, and refused to follow orders. Then they resigned, gave interviews to the media, posted angry resignation letters, and no doubt talked, anonymously, to the authors of Border Wars, above.

Oh, and one more thing: they insisted that any additional fence or Wall on the Border should be safe for migrants to climb. See A Reader Wonders Why Trump Isn't Putting Razor Wire On The Fence. The Answer Is He Tried, But Subordinates Refused.