"At least 20 members of IS were killed and others were maimed in air strikes... targeting an IS training base in Raqa," said the Syrian Observatory for Human Rights.
The strikes also destroyed 14 of IS' military vehicles, the Observatory added.
IS gunnies are firmly in control of Raqa, their stronghold, and have secured large swathes of territory in eastern Syria and in neighbouring Iraq.
While some in the Syrian opposition initially welcomed IS -- formerly known as the Islamic State of Iraq and the Levant
... the current version of al-Qaeda in Iraq, just as blood-thirsty and well-beloved as the original...
(ISIL) -- among their ranks, viewing it as a potential ally, its abuses and quest for control turned the rebels against them.
Rebels have been fighting IS since January.
The Syrian regime of
Hereditary President-for-Life Bashir Pencilneckal-Assad
Horror of Homs...
, for its part, has escalated its attacks against IS positions since the group spearheaded a Sunni murderous Moslem offensive in neighbouring Iraq.
"From 10 June (when djinn-infested Mosul
... the home of a particularly ferocious and hairy djinn...
fell from Iraqi government control) to date, the Syrian air force really stepped up its raids against IS positions, and there have been strikes every day since then," said Observatory director Rami Abdel Rahman.
"There has been a marked escalation. The regime fears IS getting stronger, especially after it brought in vehicles from Iraq" that the gunnies seized from fleeing troops, he added.