Sayyid Azim, Associated Press
In this Friday, Aug. 25, 2006 file photo, then Sen. Barack Obama, right, and his wife Michelle Obama, left, and their two daughters lay a wreath in memory of the more than 200 people killed following a massive truck bomb on Aug. 7, 1998, at the August 7 Memorial Park in Nairobi, Kenya. More than 15 years after al-Qaida destroyed the U.S. Embassy in Nairobi with a massive truck bomb that killed more than 200 people, fear is rising that U.S. diplomatic personnel and property could again be targeted.

NAIROBI, Kenya — The armed U.S. Marine stood behind sandbags atop the U.S. Embassy in Nairobi and looked through binoculars. What he saw was a busy street lined by a few diplomatic missions that officials fear could be targeted by Islamic militants.

Fifteen years after al-Qaida destroyed the U.S. Embassy in Nairobi with a truck bomb that killed more than 200 people, fear is rising that the U.S. could again be targeted.

Intelligence has been circulating recently that American interests are the next intended target for al-Shabab, an al-Qaida linked group in Somali, said a Kenyan police official who insisted on anonymity to talk about security matters.

U.S. Ambassador Robert Godec last week told a town hall meeting: "We know that there's a threat, and we know it's serious."