"Turkey is part of the coalition that is fighting against Assad. However, they have also been somewhat less than discriminating in who they have funded in the fight against Assad," Smith stated on Tuesday.
Turkish support for anti-Assad rebels raises the "potential for conflict," Smith noted, as Russia has been providing military assistance to President Assad since September.
"Turkey is supporting rebels right across their border that are fighting Assad, while Russia is fighting against those rebels," Smith explained, describing the situation as "complex."
Smith affirmed that the United States still needs Turkey as an ally in the fight against Daesh. "The trouble is, it is complicated to get there because of all the conflicting alliances."
On Tuesday, US military officials criticized Turkey for failing to secure its porous border, which has allowed for the movement of Daesh fighters and resources out of Syria.
Russia has also renewed its criticism of Turkey for turning a blind eye to Islamic militants, particularly following Turkey’s shoot-down of the Russian Su-24 fighter jet last week.