Because the logical place to hold the upcoming "Operation Eager Lion" joint US-Jordanian war games would be right on the Syrian border.
Because there's no possible way that war games on the Syrian border could possibly inflame a situation that is already beyond volatile.
Because war games on Syria's border would mean US troops won't have too far to go just in case Assad crosses another one of those imaginary "red lines" again.
This is Obama inching his way into America's next war without it being too obvious. After all, you don't want to unduly alarm the electorate.