Poker, an old American card game, which everyone used to know. One of the things you learn in poker is a poker face. You don't let the other players know what your cards are. If they think your cards are weak, they will bet heavily, and when your strong hand wins, it will win real money, rather than just penny antes. You never smile as bets are going down.
"Negotiation" with the IS terrorists is like poker. Never show your cards. When they don't know, they will worry about what might happen to them. You never say "No boots on the ground". That merely weakens your bargaining position. Most Iraqi's have painful experience with American soldiers who could kick their asses in every engagement. There is some useful fear there. As soon as our President says " No boots on the ground" that useful fear is canceled out.
Obama is saying "no boots on the ground" to please his left wing US voters, not to help negotiations. He clearly puts domestic politics above asserting American power abroad. He would clearly rather let the terrorists win in Iraq than offend his left wing base at home. And that is shameful.