Retired four-star Gen. Jack Keane joined Chris Wallace on Fox News Sunday to evaluate a week of airstrikes in Syria and how much damage has been done to ISIS.

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"Syria represents the center of gravity, frankly, for ISIS," Keane explained, adding that's because their base of operations is in the city Raqqa and their support operations for Iraq are all based in Syria.

According to Keane, the primary targets of U.S. and coalition airstrikes thus far have been oil refineries in the southeast of Syria that are controlled by ISIS, staging bases further to the north that funnel troops and resources into Iraq, Raqqa itself and the city of Aleppo in the northwest, where the new terror group Khorasan is based.

Noting that these airstrikes are "just the beginning," Keane said the main goal is to deny ISIS freedom of movement and take away their ability to attack at will.

"When that stops happening, then we'll know this air campaign is successful."

Watch the clip from Fox News Sunday above.

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