Nearly simultaneous truck-bombs exploded outside two synagogues in Istanbul Saturday killing 23 people and leaving more than 300 wounded. Two Arabic-language publications said yesterday that they had received separate statements asserting al Qaeda’s responsibility for the attack. The New York Times reports that one of the groups, Abu Hafs al-Masri Brigades, has claimed credit for numerous events that al-Qaeda has not been involved with, such as last summer’s big blackout.