While Islamic Jihad has said it would not disrupt the truce, according to Hamas, it did fire rockets into Israel Wednesday. The militants said the attack was in response to Israel killing 10 of its members over the past two days.
Israelis are equally tentative. Many say that the cease-fire will give Hamas time to rebuild. Others are concerned the deal emboldens Hamas vis-á-vis Fatah, which controls the West Bank.
"It's not clear to what extent Hamas can maintain a cease-fire, especially in terms of imposing it on some of the non-Hamas organizations, and even among some of the Hamas people themselves," says Ephraim Kam, deputy director of the Institute for National Security Studies (INSS), a think tank at Tel Aviv University.
"Among the security establishment in Israel, the expectation is that it won't hold for long," he adds. "Many feel that the [truce] will just be a postponement of the unavoidable clash which might take place under even worse conditions, in which Hamas will have more sophisticated weapons and be better trained."
But, he acknowledges, that formula works both ways. "The IDF [Israel Defense Forces] will also be able to strengthen itself to fight Hamas, if a showdown is going to take place."
Hamas officials in Gaza say they will have no difficulty enforcing the deal, and that it's up to Israel to make sure that it sticks.