JERUSALEM—The Israeli military says a projectile fired from the Gaza Strip Thursday evening landed in the south of the country, breaking weeks of relative cross-border calm. There were no reports of damage or casualties. Sirens warning of incoming rockets sounded in the Negev Desert town of Sderot and its surroundings. In response, Israeli aircraft early Friday hit three facilities belonging to Hamas, the militant group ruling Gaza. The airstrikes targeted a weapons manufacturing site, a tunnel for arms smuggling, and a training site, the military said. No Palestinian group claimed responsibility for the rocket fire from the Palestinian enclave. Israel usually blames Hamas group for any violent act emanating from Gaza. The attack comes at the end of Independence Day, which honors the creation of Israel after the end of the British Mandate in 1948. Hamas and Israel observe an unofficial truce brokered by regional mediators, including Egypt and Qatar. …