The US and Arab allies bombed Syria for the first time on Tuesday killing dozens of Islamic State (ISIL) fighters.
US Central Command said Bahrain, Jordan, Qatar, Saudia Arabia and the UAE took part or supported the strikes against ISIL targets.
The targets of the air and missile strikes included the headquarters of ISIL in Raqqa city, northern Syria.
Dozens of militant fighters were killed in the strikes that hit at least 50 targets in the east of Syria.
ISIL vowed revenge for the attacks.
Separately, the US acting alone launched strikes against the Al Qaeda-linked Nusra front.
The strikes hit targets in Aleppo and Idlib to “disrupt imminent attack” against US and Western interests by “seasoned al Qaeda veterans.”
At least 50 fighters and eight civilians were killed in that attack.
The Nusra Front is al Qaeda’s official Syrian wing and ISIL’s rival.
The Syrian government had previously said that any military action taken without its consent would amount to an act of aggression.