US security teams landed at the US Embassy in Beirut on Sunday to start planning the evacuation of Americans from war-torn Lebanon, the embassy said. Witnesses said two helicopters flew in from over the Mediterranean and landed on the embassy grounds, located on a fortified hilltop in the north Beirut suburb of Aukar. "The arrival of the teams is an important first step in facilitating the safe departure of Americans who want to leave Lebanon," an embassy statement said. It said the teams were making arrangements "to provide secure transportation for American citizens who wish to depart Lebanon." There are an estimated 25,000 Americans living or working in Lebanon, but US officials said they assume that far fewer would choose to leave.