US embassies around the world are being targeted by protests against the film Innocence of Muslims, which the Muslim world considers blasphemous. Four persons died in Thursday\'s attempted assault on the US embassy in Sanaa, and the protests have spread from Casablanca to Jakarta, from Dacca to Tel Aviv, from Tunis to Tehran, forcing embassies of every stripe to beef up their defenses. US President Barack Obama treads the twin line of condemning the film and placating his Arab allies on the one hand, on the other sending two Navy destroyers as well as 200 Marines to protect his missions in Libya. \"The United States government had absolutely nothing to do with this video. We find it disgusting and reprehensible\", US Secretary of State Hillary Clinton said on Thursday. \"Every responsible leader should now stand up and condemn all violence\", Clinton said. Obama spoke with Egyptian President Mohamed Morsi on security cooperation, and to ask his Egyptian counterpart for more protection for the US embassy in Cairo, where demonstrations have been going on since Tuesday, and where more than 200 protesters ended up with tear gas poisoning in today\'s protest. Moments before flying to Brussels on what is his first mission to a Western country, Morsi said that the Prophet Mohamed \"is an untouchable red line\". Obama on Thursday also spoke with newly installed Libyan Premier Mustafa Abu Shagur to set up a joint investigation into the Tuesday night attack on the US consulate in Benghazi, in which US Ambassador Chris Stevens and three American staff members were killed. \"No act of terror will go unpunished\", the US commander in chief said later on Thursday, as Shagur confirmed today\'s arrest of an undisclosed number of suspects from undisclosed organizations. Al Qaeda, which has claimed responsibility for the Benghazi attack, remains very much a suspect.