From NBC's Robert Windrem
A senior U.S. counter-terrorism official confirms that Indian authorities have found the names of several high-ranking members of the Pakistani-based group, Lashkar-e-Taiba, in the satellite phone used by one those who carried out the attacks in Mumbai. Lashkar is considered a terrorist group by the U.S. government.
Morever, there is evidence that calls were placed to some of the Lashkar leaders from the satellite phone.
Among those on the list: Yusuf Muzammil, head of Lashkar-e-Taiba's operations unit.
A U.S. intelligence official says, while it is possible that the attacks in Mumbai were "not necessarily a top-down operation ... it's not yet clarified" and that there are strong indications this was a Lashkar operation.
The official noted that the sole terrorist captured after the attacks had confessed to a Lashkar connection.
"Lashkar has some explaining to do," added the official.
Pakistani officials are reluctant to confirm that Lashkar controlled the operation, suggesting it could be a rogue operation from within Lashkar, noting the organization has more than 5,000 members.
Pakistani officials are concerned that India could attack Lashkar's headquarters, which is in Lahore -- deep inside Pakistan.
Lashkar also is known to have training camps just inside the Pakistani border.