US-led forces have struck in Syria, reportedly killing dozens of militants. Targets included the Islamic State group's stronghold of Raqqa in the north of the country, with Arab states also taking part in the mission. So who's on board, and to do what? How will the permanent members of the UN Security Council react? And just over a year after it allegedly carried out chemical attacks on its own people, does the Syrian regime now stand on the right side of history?