CAIRO - Egyptian jets bombed a gathering site of Sinai-based Islamist militants, killing 12 and destroying several four-wheel-drive vehicles, the military said on Tuesday.An Islamist insurgency in the rugged, thinly populated Sinai Peninsula has gained pace since the military overthrew President Mohamed Morsi of the Muslim Brotherhood, Egypt's oldest Islamist movement, in 2013 after mass protests against his rule.The air strikes "resulted in the killing of 12 highly dangerous ... leaders of Ansar Bayt al-Maqdis," the military said in a statement. It did not say when the aerial bombing took place.Ansar Bayt al-Maqdis, Egypt's most active militant group, swore allegiance to Islamic State in 2014 and adopted the name Sinai Province. It is blamed for the killing of hundreds of soldiers and policemen in attacks since then. The group has turned its guns on Egyptian Christians in recent months, killing more than 100 in bombings at Coptic churches.President Abdel Fattah al-Sisi carried out air strikes on militants in Libya in response to a deadly attack on Coptic Christians earlier this month that left at left 29 killed.Egypt's military say it has killed thousands of militants in operations in Sinai. Residents of the Sinai say the high death rates include civilians.