"I had to ask myself, what the hell does he think we've been trying to do for the last 14 years in terms of al Qaeda?" Retired Army Lt. Gen. Mark Hertling
told Anderson Cooper on AC360 on Tuesday.
At a rally in Greenville, North Carolina, Trump said that on day one of his presidency, he would convene his top generals and give what he called a "simple instruction" to in 30 days submit to the Oval Office "a plan for soundly and quickly defeating ISIS."
The former commanding general decried Trump, calling his orders "simplistic" and insulting to individuals working to defeat ISIS.
"It shows a complete lack of understanding of the threat and the ways to fight it," Hertling said. "It's a sophomoric approach to elements of national security policy because if he's just calling in the military, he's missing the point that there are several other elements of national security that will help defeat ISIS."
Hertling argued that the US has made some good advances against ISIS.
Democrats have highlighted statements Trump has made about military leaders in the past, most notably criticizing him for saying in November 2015,
"I know more about ISIS than the generals do, believe me." Hillary Clinton brought up the line in July, saying, "No, Donald, you don't."
Trump's comments came on the same day his campaign released a letter signed by 88 retired military leaders endorsing his presidential candidacy, including four four-star generals and 14 three-star flag officers.
Hertling said he was surprised by the letter praising Trump.
"I didn't recognize many of those names as being there in the fight with me over the last 16 years," Hertling said. "There aren't a whole lot of names in the fight against al Qaeda or several of the other forces."
He said most of the names on the list are Navy admirals who were not on the ground during the war against terror.
served in the Army for 37 years.