US President Barack Obama has vowed to do everything possible to protect Americans overseas as he honoured the diplomat and three staff members killed in an assault on a US consulate in Libya.
The bodies of US Ambassador Chris Stevens and embassy workers Sean Smith, Tyrone Woods and Glen Doherty were returned to US soil three days after they were killed in a rocket attack in Benghazi.
The President joined his Secretary of State Hillary Clinton in paying tribute to the victims in a ceremony at Andrews Air Force Base in Maryland as the coffins were carried from their plane.
Washington Correspondent Robert Moore reports:
Mr Obama said the men were "four patriots who loved their country, chose to serve it and served it well. They knew the danger and they accepted it."
"They lived and embodied the American ideal," he added.
The President then vowed to do "everything in our power" to protect US citizens serving abroad.
Secretary Clinton offered her "most heartfelt condolences and deepest gratitude" to the four families of the deceased and said the service given by their loved ones was "at the heart of what makes America great and good."
Mrs Clinton urged Americans to carry their memory into the future.
"We will wipe away our tears, stiffen our spines and face the future undaunted," she said.
Mrs Clinton said Americans would continue to work "together, helping and protecting one another, just like Sean, Tyrone, Glen and Chris always did."
Tuesday's Benghazi attack, which US officials believe could have been planned in advance, emerged from a protest blaming America for a US-made film they said insulted the Prophet Mohammed.
The film has sparked protests, some of them deadly and still continuing, at US embassies across the Muslim world.
Mr Obama and Mrs Clinton again both condemned the Californian-made film, while distancing the US Government from its creation, and denounced the violence being played out across the globe.