The Jordanian military says dozens of its fighter jets have bombed Islamic State targets, including training centres and weapons storage sites.
State TV showed footage of the strikes, including one which set off a large ball of fire after impact.
Jordan has already said it would respond harshly after a captured Jordanian pilot, Moaz al-Kasasbeh, was burnt to death by the militants.
Earlier today, the Jordanian king, King Abdullah, promised a 'relentless war' against the militants.
On their return, the fighter jets flew above the village of al-Kasasbeh, coinciding with a visit to the town by King Abdullah.
A video has been posted to YouTube showing Royal Jordanian Air Force jets preparing to launch the attack. In the video, Jordanian men and women are seen signing the fighters' bombs.
