If hundreds of terrorists are released in exchange for abducted IDF Cpl. Gilad Shalit, they will pose an immediate threat to Israel, a high-ranking defense official said. Should the government accede to the demand, the official said, the IDF would need to modify the way it operates in the West Bank. Prime Minister Ehud Olmert has expressed "disappointment and reservations" over the list of prisoners, which is said to include as many as 450 murderers. "The Palestinians in prison have the terror know-how and the influence over the terror groups," the defense official said. "If they are released they will be taking those qualities with them and we will need to be prepared."