According to CNN, the U.S. is considering sending regular combat ground troops to Syria, supposedly to fight ISIS. The article doesn’t say how many. There are already advisers and special forces there.
This reminds me of the description in The Best and the Brightest of how the Vietnam War started and later escalated. And there would be some similarities in fighting a shadowy and ill-defined enemy. The strange thing though is that by fighting rebels who are fighting the Syrian government, we would be helping the Syrian government, which is allied with Iran and Russia, supposedly our enemies and the enemies of our allies like Israel and Saudi Arabia. It’s all very murky and confusing, and kind of obviously a bad idea.