Police in Nigeria, which faces an Islamist insurgent threat, ordered 24-hour security around all foreign embassies on Thursday after gunmen in Libya enraged over a U.S. film about the Prophet Mohammad killed the U.S. ambassador there.U.S. embassies in Yemen and Egypt were also attacked by demonstrators on Thursday and U.S. warships headed to Libya after an embassy siege there on the 11th anniversary of al Qaeda’s September 11 attacks on the United States.Nigerian authorities fear an Islamist backlash as well, possibly after Friday prayers this week."The Inspector-General of Police (IGP), Mohammed Dahiru Abubakar, has placed all police formations across the federation on red alert,” a statement from the Nigerian police said."The IGP has directed  24-hour water-tight security in and around all embassies and foreign missions in Nigeria as well as other vulnerable targets.”The Nigerian Islamist sect Boko Haram has killed hundreds of people this year as it aims to revive an ancient Islamic state in the modern West country of 160 million people, split roughly evenly between Muslims and Christians.Boko Haram bombed the offices of Nigerian newspaper This Day in April because of an article written years before about the Miss World beauty pageant and the Prophet Mohammad that they said was blasphemous to Islam.The sect also carried out a suicide bombing on the United Nations building in the capital Abuja last year.The U.S. embassy in Abuja told Reuters on Thursday that security was at heightened levels there, but that it had been that way for several months anyway.