By David Morgan
WASHINGTON (Reuters) - The United States does not believe Iran has a nuclear weapon but the danger Tehran will acquire one is an "immediate concern," U.S. intelligence chief John Negroponte said on Thursday.
Negroponte also told a Senate committee looking into the range of threats to the United States that al Qaeda was still plotting and preparing for attacks on the United States.
"We judge that Tehran probably does not yet have a nuclear weapon and probably has not yet produced or acquired the necessary fissile material," Negroponte, director of national intelligence, told the Senate Select Committee on Intelligence.
But he added, "The danger that it will acquire a nuclear weapon, and the ability to integrate it with the ballistic missiles Iran already possesses is a reason for immediate concern."
The committee was looking at the proliferation threat posed by Iran on the same day the International Atomic Energy Agency considered whether to report the Islamic Republic to the UN Security Council over its nuclear program.
Iran insists its nuclear ambitions are purely to develop nuclear power.
Negroponte also said that while much of al Qaeda's leadership from the time of the September 11 attacks on the United States had been eliminated, its "core elements still plot and make preparations for terrorist strikes against the (U.S.) homeland and other targets from bases in the Pakistan-Afghanistan border area."
"The group will attempt high-impact attacks for as long as its central command structure is functioning and affiliated groups are capable of furthering its interests, because even modest operational capabilities can yield a deadly and damaging attack," he said.
An attack using conventional explosives remains the "most probable scenario," but al Qaeda remains interested in acquiring chemical, biological, radiological and nuclear materials or weapons, he said.
Attacking U.S. territory, U.S. interests abroad and allies overseas remained al Qaeda's top priorities -- in that order, he said.
Nearly 40 terrorist organisations, insurgencies, cults and other groups have used, possessed or expressed an interest in chemical, biological, radiological or nuclear agents or weapons, Negroponte added.
Negroponte also said the slow pace of economic and political change in most Muslim nations continued to fuel global Islamist militant movements. He said the United States was not immune to homegrown militants, adding that prisons were fertile ground for recruitment.
QUESTIONS ON EAVESDROPPING PROGRAM
The Senate committee's annual hearing on worldwide threats gave lawmakers their first chance to grill intelligence leaders publicly about President George W. Bush's domestic eavesdropping program at the National Security Agency.
The program has raised an outcry from Democrats and some Republicans who question whether Bush overstepped his authority. The administration has said it was needed because existing provisions for eavesdropping were not flexible enough.
Sen. Jay Rockefeller of West Virginia, the senior Democrat on the committee, accused the White House of being too secretive about the program, involving eavesdropping without a warrant on e-mails and phone calls between people in the United States and suspected militants abroad.
He and committee Chairman Pat Roberts of Kansas were briefed by the administration, but Rockefeller complained the White House was not providing the full committee with enough intelligence.
"A decision has been made by the White House to overly restrict congressional access to key information about the NSA program while, at the same time, it opens the floodgates of its public relations campaign in support of the program," he said.
(Additional reporting by Caroline Drees)