By Phil Stewart WASHINGTON (Reuters) - The United States on Thursday called on Israel to do more to protect civilians in its military offensive in Gaza and condemned an Israeli strike on a U.N.-run school, even as it defended moves to resupply its close ally with ammunition. The White House reiterated its position that it was Israel's right to defend itself and described the resupply of ammunition disclosed as the fighting raged this week as "routine." White House spokesman Josh Earnest rejected suggestions that resupplying the Israelis might prolong the conflict, saying it was "part of a routine foreign military sales delivery." "The requested items were readily available and were provided as they have been on numerous other occasions," Earnest said. Israel says 56 of its soldiers and three civilians have been killed.
U.S. Secretary of State John Kerry on Friday called the 72-hour ceasefire agreed to by Israel and Hamas in their conflict in the Gaza Strip a "lull of opportunity" and said it was imperative that the sides make their best efforts to find common ground. Kerry said Egypt's foreign minister will invite the Gaza ceasefire parties to take part in "serious" negotiations in Cairo and that the United States plans to send a small delegation to the talks. "This is a lull of opportunity," Kerry told reporters. "... It is imperative people make the best effort to try to find common ground." (Reporting by David Brunnstrom;