At the minute, the US and the Russian governments are debating about the future of Syria and how to proceed. One of the main points of discussion is regarding the withdrawal of Hezbollah and other militias. The US has made it clear that all armed forces from abroad that are supporting the Syrian regime need to leave. First and foremost, Iran’s Revolutionary Guard Corps (IRGC), as well as the Lebanese Hezbollah and Afghan, Iraqi and Pakistani militias.
The United States had as good as agreed that the Russian project aiming to end the conflict politically in Syria regardless of the survival of Bashar al-Assad was the way to move forward. But then the chemical weapons attack on Khan Shaykhun happened.