The Marine stood behind a camouflaged sandbag bunker atop the United States Embassy in Nairobi and scanned the horizon with binoculars. What he saw was a busy street that officials fear is full of targets for an attack by al-Qaeda-linked militants because diplomatic missions are in the neighborhood, AFP said.More than 15 years after al-Qaeda 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. Armed Marines are now stationed on the embassy's roof, one indication of recent security upgrades.Intelligence has been circulating in the region the last two months that American interests are the next intended target for al-Shabab, an al-Qaeda linked group in Somalia responsible for last year's attack on Nairobi's Westgate Mall, said a Kenyan police official who insisted on anonymity to talk about security matters.The terror group has also shown interest in attacking the U.S. military base in Djibouti, just north of Somalia, and there were indications that the U.S. Embassy in Ethiopia was being considered as a target last year, said Matt Bryden, the former head of the United Nations Monitoring Group on Somalia and Eritrea and a top expert on al-Shabab.Ambassador Robert Godec last week told some 400 Americans at a town hall meeting: 'We know that there's a threat, and we know it's serious.' Diplomats have indicated that global terrorists affiliated with al-Qaida are moving in to the region.The embassy looks likely to scale back the number of U.S. personnel stationed in Kenya, in part by reducing or moving the East Africa mission for the U.S. aid agency USAID.The embassy's top security officer, Marion Cotter, detailed the evolution of terror in Kenya: The first improvised explosive device explosion was in August 2012. Then militants began using remote controlled IEDs and brought into Kenya a massive, complex car bomb this year that the FBI disarmed. Militants now also use multiple IEDs in a single attack, and gunmen on suicide missions.'Westgate was the first time there was really a Western target since 2002,' Cotter told the U.S. audience, referring to the September attack on an upscale mall by four gunmen that killed at least 67 people, many of them foreigners.In a statement to The Associated Press after the town hall, Godec, who was stationed in Nairobi during the 1998 embassy bombing, said the embassy is continually evaluating its security posture and updating security based on threat information analysis.The embassy on Thursday told U.S. citizens to be cautious in large groups at bars or restaurants, for instance, when watching the upcoming soccer World Cup. Al-Shabab detonated bombs in neighboring Uganda as people watched the World Cup final four years ago, killing 70 people.Late last month an al-Shabab leader named Fuad Mohamed Khalaf, also known as Shongole, said Islam's flag will fly over Washington and New York. In an earlier speech, al-Shabab leader Ahmad Godane foreshadowed attacks on French interests, Bryden said, which may have referred to a suicide bomb attack at a restaurant in Djibouti, where French forces are also stationed.The U.S. Embassy sits across from the street from the U.N. headquarters in Kenya. Kenya recently deployed more security forces on the street.Kenyan President Uhuru Kenyatta in a speech on Wednesday said his government is committed to protecting the country. The military is planning to station troops on roads potentially used by al-Shabab to enter Kenya.'Serious tests lie before us,' Kenyatta said. Click here to read full news..