Amateur footage shows gangs of armed men attacking and entering the US Consulate in Benghazi, Libya.
The protest at the consulate was sparked by outrage over a film produced by an American film maker ridiculed the Prophet Mohammed. Cars were set alight and the building was looted.
President Obama vowed to do everything possible to protect Americans overseas as he honoured the four killed in the Libyan consulate attack.
Both Barack Obama and Mitt Romney know how they respond to the spread of violence across the Arab world could affect their election hopes.
Mitt Romney has attempted to score cheap, tawdry political points in the wake of the worst attack on the US diplomatic service in decades.