The U.S. intelligence community is monitoring a specific stream of classified information suggesting the terror group believed to be behind the Nairobi shopping mall attack may be planning new attacks in East Africa, particularly in Kenya, CNN has learned.
Two U.S. officials said the information does not include details of a target or date. But it is the first detailed indication that they may have information to validate threats made by Somali-based al-Shabaab that more attacks were planned after the attack on the Westgate shopping mall in Nairobi.
"We are concerned," one official said.
"There are data points that worry us. Our intelligence is focused on how do we prevent any more attacks," the other official said.
Both have access to the latest intelligence. They declined to be identified due to the sensitive nature of the information.
Both said the classified information is separate from public claims and tweets by al-Shabaab threatening another attack.
The new information emerged subsequent to the attack and standoff at the Westgate Mall between last Saturday and this past Tuesday that killed at least 67 people.
It is also part of the reason for the State Department's worldwide caution notice on Wednesday.
The notice said "credible information indicates terrorist groups also seek to continue attacks against U.S. interests in the Middle East and North Africa. The U.S. government remains highly concerned about possible attacks against Americans, facilities, businesses, and perceived U.S. and Western interests."
The State Department on Friday reissued a separate warning -- first put out in July -- about travel specific to Kenya, saying Americans already there or planning to go there should "evaluate their personal security situation."
While the officials wouldn't discuss classified intelligence, it's well understood that the U.S. monitors and intercepts telephone and Internet communications, which generally spike after a successful attack. All of the so-called chatter is being analyzed for clues.
CNN also learned military and security personnel at the U.S. Embassy in Nairobi -- within minutes of realizing the severity of the mall attack -- tapped their emergency stockpile of gear and began providing Kenyan forces with night vision equipment and tear-gas type riot-control chemicals.
The Pentagon still has not spoken publicly about any effort to help the Kenyans, but several U.S. officials confirmed those details to CNN.
A priority now is to gather fingerprint and DNA information from the scene to try to determine the identities of any of the dead attackers, as well as perhaps suspects who fled the scene, according to an Obama administration official with access to the latest information.
U.S. and international experts are assisting in that effort. But there is still no confirmation that any of the attackers were American citizens as al-Shabaab has claimed, U.S. officials said.
So far, it appears there was no direct connection yet between the attackers and the East African cell of al Qaeda. That cell, however, remains under close scrutiny by American intelligence.