ROMANS: A troubling development in the war against ISIS. Pentagon officials believe the terrorist group is using chemical weapons against Kurdish fighters in Iraq. We get more from CNN's chief national security correspondent, Jim Sciutto.</s>JIM SCIUTTO, CNN CHIEF NATIONAL SECURITY CORRESPONDENT: Christine, the U.S. believes it has credible information that ISIS used this chemical agent, mustard gas, extremely powerful, dates back to World War I, outlawed in fact after World War I. Why do they find it credible? Basically the symptoms of these Kurdish soldiers who were attacked with it in Northern Iraq both breathing difficulty after the attack, but also signs of blistering on their skin. Mustard gas is a blistering agent. Two explanations for how ISIS could have gotten this. Either they overran old Iraqi or Syrian weapons caches or U.S. officials say it's also possible that they figured out how to make this themselves and weaponize it. Both of those explanations frankly are alarming. It would be a real concern. U.S. officials say, listen, in terms of the battle field calculus, this is not a major game changer, but these are weapons of fear, much like terrorism and beheadings that ISIS has been carrying out. That's a factor on the battlefield, but also this, you've heard some U.S. officials mention the possibility of putting U.S. soldiers closer to the frontline either as spotters for airstrikes or possibly forward deployed advisers. This, of course, would then have to be added into the dangers that they may face on the battlefield, certainly part of that calculation. It is regardless of the explanation and still they have to confirm that this was mustard gas. If it is confirmed, this is a very alarming development -- Christine.</s>ROMANS: It certainly is. Jim Sciutto, thank you for that. Danger in the sky, pilots reporting more near collision with drones. We have new information for you after the break.
Does ISIS Have Chemical Weapons?.