Israel launched fresh strikes against Islamic Jihad targets in Gaza early Friday in response to rocket fire, underscoring the fragility of a ceasefire agreed after an escalation that killed 34 Palestinians. The ceasefire began on Thursday following two days of fighting triggered by Israel’s targeted killing of an Islamic Jihad commander. The Israeli military said it carried out new strikes overnight against Islamic Jihad, the second most powerful Palestinian militant group in the Gaza Strip after Hamas.