I'm Jack Keane, retired four-star general, former Vice Chief of Staff of the U.S. Army and a member of The Cipher Brief network. A U.S. jet shot down a Syrian warplane that was dropping bombs near U.S. led, anti-ISIS fighters in Syria. In response, Russia has threatened to target U.S. and coalition aircraft flying over Syria east of the Euphrates River. So what does this escalation of tensions between the U.S. and Russia mean? Here's my perspective, In My Own Words, no holds barred.