militants in East Africa are now posing new worries for the President's trip to Kenya this week. CNN has learned that, in just the last week, the U.S. military has conducted nearly half a dozen secret air strikes in Somalia against al Qaeda's Africa affiliate because U.S. intelligence indicated an attack against Kenyan troops there was imminent, according to defense officials.
The Pentagon isn't saying much, but the strikes may be timed to the President's visit.
"This sends a very clear message to Al-Shabaab not to try to attempt anything against the President," says Seth Jones, a Rand Corporation analyst.
U.S. officials do not believe Al-Shabaab can get anywhere near the President, but there are others reasons to worry.
Jones suggested that the group would look for more vulnerable targets to attack to show Kenyans their government cannot keep them safe and to draw attention away from the Obama visit.
"What's most likely is not an attack against a U.S. government official like the President, but an attack that happens while the President is there," he said. "Security for the president is likely to be very significant and that means what Al-Shabaab
is likely to do, based on what it has done very recently, is go for a soft target."
That could include shopping malls and schools, which the group has attacked in the past.
U.S. officials told CNN that in recent days there is growing social media and Internet chatter among the Somalia-based group about the President's visit.
"They all know he is coming," one official with access to the latest intelligence told CNN.
In addition, a Kenyan flight bulletin outlining some details of the President's trip has been released, including when airspace in Nairobi would be closed because of the arrival and departure of Air Force One.
Such details are usually kept secret for security reasons, but administration officials so far are brushing off the publication of this information, saying there are no public details about the President's trip that pose a risk to his security.