Will the U.S. have to rethink stance against Assad amid ISIS threat?

As President Obama meets with European leaders at the NATO summit Thursday, the fight against ISIS looms over America's foreign policy agenda.

In addition to going after the terror group in Iraq and targeting the group's leaders, former CIA deputy director Mike Morell said finding a solution in Syria needs to be a part of any strategy the U.S. pursues.

"That's the much more difficult problem because we also need, in addition to airstrikes, we need a military on the ground in Syria to take these guys on," Morell, now a CBS News consultant, said Wednesday on "CBS This Morning."

"The only military around is [Syrian President Bashar] Assad's military, and as you know, we're fighting Assad as well."

President Obama has repeatedly called for Assad, who has been accused of using chemical weapons against his own people, to step down amid nearly three years of violence.

While Morell said the best course of action would be to persuade Russia and Iraq to pressure Assad to leave office and work with new leadership in Syria who will help fight ISIS, that may not be realistic.

"If that doesn't work, I think we need to rethink our strategy vis-à-vis Assad, yes," Morell said.

In Iraq, Morell said ISIS should be targeted "using the Iraqi military and the Kurds backed by U.S. airstrikes, underpinned by a political solution."

On Tuesday President Obama authorized an additional 350 military personnel to be sent to Iraq to help protect U.S. facilities and personnel in Baghdad.

Morell also said getting rid of ISIS leadership is important to weaken the group.

"This is a very small leadership, a lot of command and control, a lot of sophistication. We need to take them off the battlefield."

In order to do so, careful planning has to take place.

"You need very good intelligence on where they are and then you either need to put guys on the ground to go get them or you need to use unmanned aerial vehicles to kill them," Morell said.

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And while ISIS is garnering the majority of media attention, Morell added that Libya should also be monitored, especially because the situation there is "very similar to what happened in Iraq."

"The extremists there, the al Qaeda-affiliated groups there, are making a move to take over the country. They took Tripoli this weekend," Morell said. "A lot of people aren't focused on what's happening in Libya because what's happening in Iraq is dominating it, but we need to focus on Libya as well."