Retired Gen. Stanley McChrystal said this morning that simply sending new weapons to the Iraqi forces is not going to make the difference in the battle against ISIS. 

Meantime, Iraq's government announced Tuesday that its military had launched a counterattack aimed at driving ISIS out of Ramadi.

Defense Secretary Ashton Carter said the problem has been the lack of will by Iraqi soldiers to fight ISIS. Carter said the Iraqi forces "vastly outnumbered" ISIS in Ramadi, yet withdrew.

McChrystal echoed that sentiment, explaining that wars are not won by superior numbers. 

"War is not math. War is about confidence," he said, adding that he believes Carter was referring more to the Iraqi government's will to fight, not just rank-and-file soldiers.

"New weapons are not going to make the difference. If war was math, everybody would add up who has the most and then you wouldn't fight because you'd know who'd win and lose, but it doesn't happen that way," he said. 

The former commander of U.S. and NATO forces in Afghanistan said a bigger commitment and more sacrifice is going to be needed to defeat ISIS. 

"This won't be the last Memorial Day where we are having to honor people who die, who have not yet died," he said.

McChrystal, author of the new book Team of Teams: New Rules of Engagement for a Complex World, was asked by Martha MacCallum about possibly sending in American ground troops to fight ISIS. 

"Should one more person have to die for this fight if we don't get the message from the top that we will do whatever it takes to defeat this enemy?" she asked.

The general responded that the Middle East needs to see American leadership. Martha pressed him on whether the administration is doing enough in that area. 

"I think we're gonna need to do a lot in the future," he answered.

Watch the interview above and hear more from Gen. McChrystal tonight, on "On the Record" at 7p ET.