The Syrian government's allies will strike at American positions inside Syria if it crosses any "red lines," Hezbollah warned on Wednesday.
The Lebanese militant group, a close ally to the Syrian government, issued the threat via its military media arm one day after American forces bombed pro-government forces in eastern Syria.
The Pentagon said Tuesday the pro-government forces were infringing on a "de-confliction" zone established to protect U.S.-backed local opposition forces, who are engaged in fighting the Islamic State group.
On its TV station al-Manar, Hezbollah broadcast footage it said was of an Iranian drone tailing an American one over eastern Syria. It said the video was proof the Syrian government's backers could strike American units at will.
Iran is a key backer of Hezbollah and the Syrian government, and is deeply involved in the Syrian civil war.
Hezbollah's military media said it was only "self-restraint" keeping pro-government forces from attacking American units.
Elsewhere in Syria, activists said at least nine civilians traveling in a van in eastern rural Deir el-Zour were killed in an airstrike, suspected to be by the U.S.-led international coalition battling IS.
