WS is launching an office in the Indonesian capital to service the embassy account, alongside a number of existing international clients.
The PR firm will support the US government's campaign to tackle anti-US sentiment and win support for its stance on terrorism.
A recent survey by the Pew Research Centre in the US found only 31 per cent of Indonesians approve of the US 'war on terror' and many view George Bush's efforts as an attack on the Muslim world.
Americans were one of the targets of the Bali bombings and there have been anti-US street protests in Jakarta.
WS's Jakarta office will open later this month and be housed in the offices of ad agency McCann Erickson, its sister company.
McCann booked the media for the US government's 'Muslim life in America' ad campaign, which ran in Indonesia last November.
The campaign - which some local media commentators called propaganda - included two-minute TV commercials showing Muslim families living happily in America.
WS's work for the embassy mostly involves community and media relations.