Conceding that angry protests are likely to continue for days, the US defence department has sent extra troops to protect "personnel and property" at America's diplomatic outposts across the Muslim world.
The deployment was revealed as the Obama administration ordered an evacuation of all but emergency staff from Tunisia and Sudan. It advised citizens not to visit either country until anger over a controversial video mocking the Prophet Mohamed has died down.
Protests have spread to at least 20 Muslim nations and were reported in Pakistan yesterday, leaving US officials anxious to prevent a repeat of last week's tragedy in Libya, where the US ambassador, Christopher Stevens, and three staff were killed at the American consulate in Benghazi. The Pentagon has "deployed forces to a number of areas in the region", said the Defence Secretary, Leon Panetta. "I think that we have to continue to be very vigilant because I suspect that ... these demonstrations are likely to continue over the next few days, if not longer."
His comments came as debate continued at home and abroad over the events that led to Mr Stevens' murder. In an interview with CBS yesterday, Libya's President, Mohammed Magarief, blamed the attack on foreign terrorists, saying his government has arrested 50 suspects with links to al-Qa'ida.
"It was definitely planned by foreigners – by people who entered the country a few months ago," he said. "They were planning criminal acts since their arrival." The security situation remained "difficult" for Americans in Libya, Mr Magarief added, noting: "It may be better for them to stay away for a little while."
Last week's deaths occurred when militants fired on the consulate with rocket-propelled grenades. At the weekend, al-Qa'ida issued a statement celebrating the attack, calling it "a great event" and urging supporters to "come together in one goal, which is to expel the embassies of America from the lands of the Muslims".
Back in Washington, the tragedy has spawned political debate. The White House continues to deny reports, first published by The Independent, that the State Department received "credible information" about a potential attack on the consulate two days before it occurred. However, CNN reported yesterday that a Libyan security official, Jamal Mabrouk, did indeed meet US officials in Benghazi last week and warned them about deteriorating security. The affair might have already damaged Barack Obama's re-election prospects, were it not for a botched reaction by Mitt Romney. The Republican presidential candidate was widely mocked for holding a press conference on Wednesday at which he said the President's reaction to the murder had influenced an "apologetic" Twitter post by a junior diplomat. It later emerged that the tweet was sent several hours before Mr Stevens died.
Mr Obama is anxious to put the affair behind him, and urged perspective in his weekly address on Saturday. "I know the images on our televisions are disturbing," he said. "But let us never forget that for every angry mob, there are millions who yearn for the freedom and dignity and hope that our flag represents."
Outside the Muslim world smaller, mostly peaceful protests continued against The Innocence of Muslims, the low-budget film which caused the controversy. In London, about 400 demonstrators gathered at the US embassy. Meanwhile, the three California-based men believed to be responsible for the film were revealed as associates of Zakaria Botros Henein, an anti-Islamic cleric from Orange County. They spent the weekend at the centre of a bizarre media circus. One of the men, Steve Klein, answered his door to reporters wearing only shorts and waving a pistol. Another, Joseph Nassrallah, who runs an anti-Muslim campaign group called Media for Christ, appeared to have gone into hiding. A third, Nakoula Basseley Nakoula, was wrapped in a bandana and taken for an interview by probation officials on Saturday. They wanted to ask about reports that he uploaded a version of the movie to YouTube using a pseudonym. Mr Nakoula, a Coptic Christian originally from Egypt, was convicted of bank fraud in 2008. The terms of his probation forbid him from using the internet and assuming aliases.
The backlash: global flashpoints
Hundreds of university students gathered in the capital, Kabul, yesterday to protest against the film. Some burned a US flag and a poster of President Barack Obama. The demonstrators and criticised the US for a lack of action against the film's makers.
Police fired tear gas and water cannon at hundreds of protesters as they tried to march toward the US Consulate in the southern city of Karachi yesterday. Police and private security guards outside the consulate also fired shots into the air to disperse the crowds of demonstrators angered by the anti-Islam "Innocence of Muslims" video produced in the US, according to Associated Press reports.
Hundreds of protesters gathered at the US consulate in London yesterday to protest peacefully against the film and listen to clerics giving speeches.
Police have reinforced security around the American Embassy in the French capital after hundreds gathered outside the building to protest over the weekend.