JERUSALEM (AP) — The cycle has become grimly familiar. Over the past three days, Israeli airstrikes on Gaza have killed 28 people, including senior Palestinian militants and children as young as 4. Palestinian militants in Gaza have fired some 600 rockets toward Israel, killing one person, setting off warning sirens as far north as the coastal city of Tel Aviv and sending tens of thousands of Israelis into bomb shelters. The most violent conflagration in months between Israel and Palestinian militants in Gaza has pitted the Israeli military against Islamic Jihad, Gaza’s second-largest militant group after Hamas. Here’s a look at the more militant Islamic Jihad that’s taking the lead in this round of fighting.