In Nairobi's "Little Mogadishu" neighborhood, paranoia drifts in the air, mingling with cooking smells and the stink of open drains.
"I'm living in a world of fear," says Ahmed Ali Ibrahim, a tall, skinny 35-year-old Somali refugee with a shrapnel scar under his skull cap. "I can't walk about freely."
Ibrahim says he fled his homeland for Kenya, seeking safety after being wounded last year in a grenade attack on African Union peacekeepers by the Shabab, the Somali militant group linked to Al Qaeda.
But now that Kenya has sent troops across the border to battle the Shabab in southern Somalia, the thousands of war-scarred, jobless refugees like Ibrahim are seen by many Kenyans as an enemy within: cousins and friends of pirates and terrorists.
"It's hard to distinguish who is who, and these people are amongst us," George Mwangi says, sitting on a shady city corner. "You cannot distinguish who is a right person and who is a wrong person to be here."
Two terrorist grenade attacks have rocked Nairobi since Kenya's invasion, a long-planned assault that was launched after the Shabab kidnapped foreigners from Kenya's northern tourist archipelago of Lamu and from a refugee camp for Somalis. The attacks, along with the Shabab's subsequent threat to unleash suicide bombings, could ignite the combustible mistrust between Kenyans and the immigrant Somalis in their midst.
The exodus from Somalia's famine was already nurturing a backlash. In addition to the vibrant immigrants of Little Mogadishu, formally known as Eastleigh, there are about 500,000 famine refugees in northern Kenya, an influx that leads to a growing refrain that Kenya has courted danger by letting in so many Somalis.
"Definitely," said Daniel Mulum, 30, an accountant. "We are in fear of being attacked."
A columnist for the Standard newspaper, Njoroge Kinuthia, wrote recently of a weekend incident in which two Somalis boarded a crowded Nairobi commuter minibus only to see the other passengers get off.
Rahma Abukar, 30, an Eastleigh cafe owner who fled the fighting in Mogadishu four years ago with her sisters and five children, has felt that sting of suspicion. "It happens every day, when we're buying food at the shops," she says, as she keeps an eye on her gas burner with its pots of simmering spaghetti and rice.
Eastleigh is a heady mix of throbbing street markets and smart new multistory hotels, what Mogadishu might have looked like if not for two ruinous decades of clan violence and the rise of the Shabab. The hotels and malls rouse jealousy from rival Kenyan businessmen, who complain that the money must have come from the piracy that has made Somalia infamous.
Kenyan politicians are warning citizens to "be vigilant" and report "suspicious characters."
"Currently, recruitment is going on, but it's being done in secret," says Muslim cleric Sheik Juma Ngao of Mombasa, who warns that extremist clerics have long been recruiting young men to fight in Somalia. Now they have evidence to point to: the chilling smile of Elgiva Bwire Oliacha, 28, who pleaded guilty to planning last week's grenade attacks and of being a member of the Shabab.
Oliacha, who converted to Islam in 2005, said he was "happy" about what he had done. Now known as Mohammed Seif, he joined the Shabab, got training in Somalia and returned to Kenya in August.
Critics say Kenya's tolerance of police harassing and extorting money from Somalis has bred resentment and alienation that could be easily exploited by Islamist extremists seeking recruits. On Eastleigh's streets, women selling khat, a mildly narcotic leaf chewed relentlessly by many Somalis, say prices have fallen by 50% recently because demand has declined since police raids in the neighborhood.
Shopkeeper Abdi Nasir Mohammed, 24, says he was forced to pay a $40 bribe demanded by police after a raid several days ago in which they arrested a refugee he was sheltering.
"They were arresting people indiscriminately," Mohammed says. "They ask, 'Do you have Kenyan ID?' If you say 'Yes' or 'No', they kick you and throw you into the police van. On the way to the police camp, they ask if you are able to pay some money.
"As much as I support the elimination of Al Shabab," he said, "I'm against the profiling of all Somalis as terrorists or Al Shabab."