FILE - In this Thursday, July 19, 2012 file photo, a damaged bus is transported out of Burgas airport, Bulgaria, a day after a deadly suicide attack on a bus full of Israeli vacationers. Israel's prime minister said Sunday, July 22, 2012 that his country is on alert for plots to kill more of its citizens overseas, after speculation that last week's deadly bombing of a tour bus in Bulgaria was a rehearsal for a spectacular attack on Israel's Olympics team. (AP Photo/ Impact Press Group)