An Islamic State militant stands next to residents as they hold pieces of wreckage from a Syrian war plane after it crashed in Raqqa, in northeast Syria, September 16, 2014. Reuters Former CIA Deputy Director Michael Morell gave a bleak assessment during an interview on "CBS This Morning" on the number of troops necessary to fully uproot ISIS from its bases of operations in Iraq and Syria.

Speaking against the backdrop of ISIS's execution video of captured Jordanian pilot Moaz al-Kasasbe, Morell spoke of the limited options facing the US-led coalition in eradicating the group.

"Unless the coalition is willing to put more ground troops into Iraq, and possibly into Syria, there is very little we can do to respond," Morell, the former second in command at the CIA, said. "I think it would take 100,000 [troops to destroy ISIS] and that will simply does not exist here and it doesn't exist in the other coalition countries."

According to Morell, the US only has two possible methods for the destruction of ISIS. The first option is to "take out the leadership." Because ISIS "is a hierarchical organization with "a small leadership," that might be enough to cripple the group.

Morell explains, though, that decapitating the ISIS leadership would be difficult without proper intelligence. And a current lack of credible intelligence means the US and coalition forces are left with Morell's other option for destroying ISIS: placing 100,000 ground troops in Iraq and Syria to weed out the group.

However, no coalition country has "a stomach for that," he says.

The video of Kasasbe's execution, which is believed to have been filmed in early January, comes during a time in which ISIS is experiencing a number of battlefield setbacks. The militants' four month siege of Kobane in northern Syria was recently broken and Kurdish forces have begun shelling Mosul, ISIS's main stronghold in Iraq.