Syrian civil war sees influx of outside groups

This week, Syrian President Bashar Assad's forces -- with significant help from Hezbollah -- re-took the strategic border town of Qusair.

On Thursday, Al-Qaeda got in the mix. In an audio recording, their leader Ayman al-Zawahri urged Sunni Muslims to join the battle, overthrow Assad, and set up Islamic rule in Syria.

Col. Cedric Leighton, president of Cedric Leighton Associates, discussed that and other top defense issues with Capital Insider.