Donald Trump has stepped in it again.

CNN reports, “Donald Trump doesn't believe there is enough evidence to blame pro-Russian separatists for last year's downing of a commercial airliner over Ukraine -- despite the fact that the U.S. intelligence community believes 'with confidence' that pro-Russian separatists shot it down...

“It's disgusting and disgraceful but Putin and Russia say they didn't do it, the other side said they did, no one really knows who did it, probably Putin knows who did it. Possibly it was Russia but they are totally denying it," touted Trump, adding, “They say it wasn't them. It may have been their weapon, but they didn't use it, they didn't fire it, they even said the other side fired it to blame them. I mean to be honest with you, you'll probably never know for sure."

Both U.S. intelligence services and Dutch investigators have determined, unequivocally, that Malaysia Flight MH17, a civilian carrier, was shot down by a Russian missile. And yet Trump insists on playing the fool. It’s a role he has come to know well. Trump’s cacophony comes just days after his fall down the rabbit’s hole of 9/11 conspiracy theories, insisting that he would have effectively prevented attacks against the World Trade Center, if he were president.

“It's disgusting and disgraceful but Putin and Russia say they didn't do it, the other side said they did, no one really knows who did it, probably Putin knows who did it."

Donald Trump

In an interview on Fox News Sunday, Trump “implied his stance on immigration could have kept out the terrorists who slipped into the United States and trained in the country to hijack the four commercial airliners” and kill American civilians on September 11, 2001. “I am extremely, extremely tough on illegal immigration. I believe that if I were running things…I doubt that those people would have been in the country,” squawked Trump in his trademark hyperbole. Thankfully, Gov. Jeb Bush crawled out of his cowardly cave and actually defended his brother for nearly the first time since his shaky campaign began:

Lending his voice to the chorus of historical revisionism, Republican presidential front-runner Dr. Ben Carson shared the opportunity to attack President Bush’s legacy, sharing similar sentiments as Trump:

GOP presidential hopeful Dr. Ben Carson [remained] steadfast in his assertion that if the United States had declared its intention to achieve energy independence after the September 11th terror attacks, moderate Arab governments would have turned over Osama bin Laden within two weeks.

"I think they would have been extremely concerned about what the ramifications of that would have been," Carson said on ABC’s "This Week." "And I believe they would have been considerably more cooperative."

Max Boot, military historian and foreign-policy analyst who has been called one of the "world’s leading authorities on armed conflict,” excoriated both candidates, laying bare the cartoonish fallacies in their statements. First Boot underscored the utter absurdity of Trump’s comments: “Donald Trump has been on an all-out offensive to do something that even few Democrats have dared to do — i.e., to blame George W. Bush for the 9/11 attacks. Is he next going to blame Franklin Roosevelt for Pearl Harbor? Trump’s reasoning, if that’s the word for it, is as specious as possible." But Trump’s weakest argument concerns his pet hobbyhorse — illegal immigrants. Boot continued:

“We had very weak immigration laws,” Trump said, adding that perhaps if Bush had had a Trump-style immigration policy, replete with “the strong laws that I’m wanting, these terrorists wouldn’t have been in the country.” Trump undoubtedly does not realize this (there is so much he does not know), but the 19 al-Qaeda hijackers were in this country legally on valid visas. They were not immigrants, legal or otherwise.

Boot then deconstructed Carson’s “novel” theory, exposing its logical pitfalls:

It’s hard to know how to disentangle a theory so loopy. In the first place, the Saudis did not have Bin Laden to hand over to us or anyone else in 2001; Bin Laden was then living in Afghanistan under Taliban protection. By that point, the Saudis had no love lost for him because he had declared a jihad against the Saudi royal family. The Saudis had stripped him of his citizenship and frozen his bank accounts. By what mechanism were they supposed to turn him over to the U.S.? And why, if the U.S. were not reliant on energy imports, would that make the Saudis more anxious to help us? Wouldn’t they be more eager to help us if we were a bigger customer of their leading export — i.e. if we were less energy independent?

As the GOP primary election heats up, we’re bound to see a lot more of Trump’s ill-considered bloviation.