Trump to Stephanopoulos: 'You can tell your military expert that I'll sit down and teach him a couple of things'

Donald Trump said in an interview on Thursday that he could teach military experts "a couple of things" about strategy. His comments came during a contentious exchange on the fight to retake an Iraqi city from the terrorist group ISIS.

The Republican presidential nominee has faced criticism for his insistence that the operation to reclaim Mosul, Iraq's second-largest city, has been a "disaster," and some military experts have blasted him for seeming unfamiliar with military strategy.

"The defense secretary is on the ground. He says they're making progress," ABC News host George Stephanopoulos said of the Mosul operation. "He's encouraged by the progress. The former dean of the Army War College says this shows Trump doesn't know a damn thing about military strategy."

Trump responded with a common refrain about the Mosul operation lacking the element of surprise.

"The Army War College. Let me tell you, the element of surprise," he said. "I've been hearing about Mosul now for three months. 'We're going to attack, we're going to attack,' meaning Iraq is going to attack, but with us, OK? We're going to attack."

He continued: "Why do they have to talk about it? Don't talk about it. Element of surprise. One of the reasons they wanted Mosul, they wanted to get ISIS leaders who they thought were, you know, in Mosul. Those people have all left. As soon as they heard they're going to be attacked, they left. The resistance is much greater now because they knew about the attack. Why can't they win first and talk later?"

Stephanopoulos then pointed out that Defense Secretary Ash Carter had said the US-led anti-ISIS coalition had killed 35 ISIS leaders so far.

"Excuse me," Trump said. "The resistance is much greater now because they knew about the attack. Why can't they win first and talk later? Why do they have to say three months before the attack we're going in? So you can tell your military expert that I'll sit down and teach him a couple of things."

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