The United States will have to sever its military assistance to the Kurdish-led Syrian Democratic Forces (SDF) battling Islamic State if the fighters partner with Syrian President Bashar Assad or Russia, a senior U.S. general said on Sunday.

The remarks by Army Lt. Gen. Paul LaCamera, who is the commander of the U.S.-led coalition battling Islamic State in Iraq and Syria, underscore the tough decisions facing the SDF as the United States prepares to withdraw its troops from Syria.

Syrian Kurdish leaders have sought talks with Assad's state, hoping to safeguard their autonomous region after the withdrawal of U.S. troops currently backing them.