Donald Trump says he could teach military leaders "a couple of things" about how to win a war.

Here's what he told ABC News' George Stephanopoulos in an interview that aired Thursday:

"Let me tell you, the element of surprise. I've been hearing about Mosul now for three months. Why do they have to talk about it? Don't talk about it. Element of surprise. General George Patton. You look at General George Patton, you look at MacArthur, you look at these great generals, and I say it all the time, they're spinning in their graves."

He added: "Why can't they win first and talk later? Why do they have to say three months before the attack, we're going in?"

The main problem with Donald Trump's criticism of the operation to retake Mosul from ISIS militants is not that his remarks are unpresidential — though they are, especially when he calls the operation a "total disaster" only a week into the fight.

The main problem with his critique is that it shows, again, that the man who claims to know "more about ISIS than the generals do" actually knows nothing about military strategy.

Surprise isn't everything

A still image taken from an Islamic State (IS) video released through the group's Amaq news agency shows an unidentified militant addressing the camera. Video said to be shot in Mosul, Iraq, on October 18, 2016. REUTERS/Reuters TV via Amaq news agency

To the civilian mind, Trump's idea that you shouldn't talk about an operation before you launch it might seem to make sense. But in modern warfare, and especially in trying to take back a city like Mosul, a surprise attack is neither feasible nor desirable — a point that actual military experts have been making for some time.

With tens of thousands of troops, artillery, and airpower to be assembled, an impending attack is not something that can easily be hidden.

"We didn't sneak up on Berlin in World War II, and we're not going to do a surprise attack on Mosul either," Michael Knights of the Washington Institute for Near East Policy told Vox.

Early warnings are also important for reducing civilian casualties.

Before the US attacked the city of Fallujah in late 2004 and cleared it of insurgents, numerous steps were taken to "shape the battlefield," including information operations such as dropping leaflets, conducting fake attacks before the real thing happened, and carrying out precision airstrikes.

Just as in Fallujah, leaflets were dropped on Mosul before the attack to allow civilians a chance to escape. This was an important step needed to protect up to 1 million civilians, unless Trump believes we should just drop a nuke on the entire city and walk away.

Psychological warfare

Then there's the psychological advantage to be gained: The Iraqi Army and US forces want to scare the crap out of the ISIS fighters. ISIS' leadership had to have known from the moment the group took over Mosul in 2014 that it would one day have to defend it from the Iraqis, who obviously want it back. It's therefore useful to create as much anxiety as possible leading up to that moment.

Doing so is cheap and, often, very effective.

Philippine Marines train with U.S. Marines attached to the III Marine Expeditionary Force/Marine Corps Installations Pacific during a fast-rope exercise Jan. 22 at Basa Air Field. U.S. Marine Corps photo by Lance Cpl. Ryan C. Mains/Released

As part of the shaping of the battlefield, the US military uses tactics like blasting Arabic messages over loudspeakers urging ISIS fighters to surrender. It drops leaflets saying much the same thing. This is the kind of thing every military does before large battles, since it often works pretty well to get at least some enemy fighters to surrender — and those fighters turn over intelligence.

"The information campaign was very effective and as important to this operation as the actual combat offensive to liberate the city," retired Marine Corps Lt. Gen. John Sattler and Col. Daniel H. Wilson wrote in their historical analysis of the campaign for Fallujah. "We stole the strategic communications initiative from the enemy and never gave it back."

It's even instructive to look back on how ISIS took Mosul in the first place. It wasn't a sneak attack at all. While logistical and political concerns contributed to the defeat of Iraqi security forces, the terrorist group was incredibly effective in using social media to "strike fear into the hearts of their enemies."

ISIS (via The Long War Journal)

Its propaganda efforts ahead of the battle led roughly 30,000 Iraqi troops to just run away, even though they were facing only about 800 ISIS fighters, The Guardian reported.

"If we're getting ready for an attack, we want the enemy doing one of two things," said one senior Marine Corps officer, who could speak only on condition of anonymity. "Either spending no time at all thinking about the possibility of an attack or spending all their time feeling the impending attack."

Trump is guessing

I've been watching this election season from the sidelines, as I don't cover politics, but because I served in the military for eight years prior to this gig, I have something to say about this.

Trump's comments on Mosul are part of a broader theme from the campaign: He doesn't know a damn thing about military strategy. For months, he has repeatedly refused to provide even general themes on how he would defeat ISIS, using the need for surprise as cover for the fact that he has no plan at all.

"We've pretty much flogged to death the idea that [Trump] is out of his depth," the Marine officer said. "He's a 1980s businessman, so he's probably pretended to read Sun Tzu. That honestly might be why he thinks deception is so important."