The United States, alongside its allies, launched the first airstrike on IS targets in Raqqa, the Syrian region believed to be a major stronghold of the terrorists group. Other countries involved in the operation were Bahrain, Qatar, Saudi Arabia, Jordan and the United Arab Emirates, though only Jordan has confirmed its involvement. Pentagon spokesman, Rear Adm John Kirby, said fighter jets, bombers and Tomahawk cruise missiles fired from ships in the region. Kirby said the assault was part of Obamas earlier avowal to degrade and destroy IS militants. The IS militants are believed to have taken a large swathe of the region and believed to have about 31,000 fighters in Syria. IS has however threatened retribution against the US. Its spokesman, Abu Mohammed al-Adnani, in a 42-minute audio statement released on Sunday said they would battle the US-led military coalition and called for attacks at home and abroad.