BLITZER: Once Syria's economic hub, the city of Aleppo is now a casualty of war. In the fight against ISIS, both the U.S. and Russia are carrying out air strikes. Now these two global rivals are trading accusations against one another of exacerbating the situation. Let's go to our Pentagon correspondent, Barbara Starr. Barbara, the U.S. is brushing off Russian claims that two American war planes bombed Aleppo. What sparked this latest uproar?</s>BARBARA STARR, CNN PENTAGON CORRESPONDENT: Well, the Pentagon says they really don't know. That they have seen the Russians do this before, making statements about U.S. military operations that the U.S clearly says are not true. So why is the U.S. saying this one's not true? Because there are no ISIS targets in Aleppo. The U.S. mission is to bomb ISIS. ISIS is not in Aleppo. Who is in Aleppo are Syrian civilians and anti-regime opponents. Opponents of Bashir al Assad, the very targets that the Russians have been bombing for some months now. So the U.S. says it's absolutely not U.S. war planes, and that the Russians they say simply are not telling the truth. The Russians say that there were two U.S. war planes bombing in Aleppo. Wolf.</s>BLITZER: Are there any planes for the Russians to cut down their number of sorties?</s>STARR: Well, at this point, the U.S. doesn't see it. You know, there are these ongoing peace talks that are very difficult right now and don't really appear to be headed anywhere the Russians have been calling for some sort of cease fire. But when you look at what is happening in Aleppo, the city in the last several days has become surrounded. Surrounded due to Russian air strikes, regime forces, Iranian backed Shia militias, hundreds of thousands of people at risk, really just barely subsisting in this city. The Russians engaging in some -- at some points in more than 100 air strikes in a 24 hour period, according to U.S.
Inside The Battle For Aleppo; Bombing Aleppo.