This meeting would not happen if someone other than Tillerson was Secretary of State. Under Obama the USA (Clinton) would go into a snit and cancel. Without Tillerson  the Russians would have cancelled. So they are still talking - good. Unless your name is Spicer or you are CEO of United Airlines, talking usually solves more problems than it creates.

Behind closed doors with cameras off Russia and USA agree Assad is an idiot who must be kept in place to serve their needs (as the idiot they both know). Chemical weapons from whatever source rocked the status quo and forced them into their current postures. Whether or not this was a false flag operation, the USA and Russia  try to avoid surprise moves that provoke major responses. Both prefer the current chess game with moves and counter moves. If Assad is behind the attacks the Russians will bring him back in line now that they know Trump will react with more than words..

The generals and military industrial complex will be very happy.