US Secretary of State Hillary Clinton has paid individual tributes to US Ambassador Chris Stevens and three embassy staff members killed in a rocket attack at the US Consulate in Benghazi.
She offered her "most heartfelt condolences and deepest gratitude" to their families as the bodies of Mr Stevens, Sean Smith, Tyrone Woodes and Glen Doherty were returned to US soil.
Clinton began her speech: "Today we bring home four Americans who gave their lives for our country and our values."
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.