Updated

U.S. security teams arrived by helicopter Sunday at the U.S. Embassy in Beirut to start planning the evacuation of Americans from Lebanon.

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, witnesses said.

"The arrival of the teams is an important first step in facilitating the safe departure of Americans who want to leave Lebanon," the U.S. Embassy said in a statement.

Click here to visit FOXNews.com's Mideast center.

It said the teams would arrange for "secure transportation for American citizens who wish to depart Lebanon." There are an estimated 25,000 Americans living or working in Lebanon, but U.S. officials said they assume that far fewer would choose to leave.

The United States said Saturday it was working on a plan to evacuate American citizens from Lebanon to the neighboring island of Cyprus.

Israeli airstrikes targeting runways have closed down Beirut's international airport. Israel also imposed a naval blockade on the country and has made road travel dangerous by targeting the main highway between Lebanon and neighboring Syria.