is something that the coalition said they did not want to have happen. they said it's been a very useful thing in terms of deconflicting that air space. they've ramped up air operations in syria the past few months against isis. this has been a real area of concern. >> so, just so folks at home understand the importance of this, it's basically intended so that you keep u.s. and russian air assets away from each other so they don't accidentally -- not necessarily fly into each other, but target each other, et cetera? >> that's right. and in addition to aerial encounters -- because, as we know, the u.s. has really started striking isis in syria, as they're moving on raqqa, isis' capital. they've ramped that operation up. there's also ground activity. there's about 1,000 u.s. troos s on the ground in syria, helping local forces fight isis. there are russian troops on the ground, helping assad's regime push into rebel-controlled areas. you really want to make sure you don't have a situation where either warplane from syria or