The U.S. intelligence chief said Sunday that internal Hezbollah groups or Syria may be to blame for the killing of a Hezbollah commander that has led the FBI to put domestic terror squads on alert in the United States.

Director of National Intelligence Mike McConnell said the United States is still reviewing the case following the death last Tuesday of commander Imad Mughniyeh. Hezbollah blamed Israel and has pledged to attack Jewish targets worldwide in retaliation. That led the FBI last week to be vigilant for possible threats in the U.S. against synagogues and other potential Jewish targets.

McConnell said he considers the threat to be primarily against Israel. But he said U.S. intelligence officials are keeping close watch and taking any necessary action to protect the United States because Mughniyeh has been "responsible for more deaths of Americans and Israelis than any other terrorist with the exception of Osama bin Laden."

Transcript: DNI Mike McConnell on 'FNS'

"It is a serious threat," McConnell said. "There's some evidence that it may have been internal Hezbollah. It may have been Syria. We don't know yet, and we're trying to sort that out."

McConnell also expressed hope that Monday's parliamentary elections in Pakistan will help produce a stable, democratic government. The elections are considered crucial to restoring democracy in Pakistan after eight years of military rule under President Pervez Musharraf.

Over the weekend, a suicide bomber in Islamabad rammed a car packed with explosives into a crowd following a rally for a candidate allied with the opposition, killing at least 40 people and heightening fears of Islamic militant violence. Most of the victims appeared to be members of the opposition Pakistan People's Party, formerly led by the slain Benazir Bhutto.

"The whole effort in our work with Pakistan, negotiations back and forth, is to see these elections be fair and free, hopefully to return them and put them on the path to democracy," McConnell said.

On other matters, McConnell:

_Reiterated his belief that the U.S. is at "increased danger" of a terrorist attack and "it will increase more and more as time goes on" because Congress did not quickly renew an eavesdropping law that expired at midnight Saturday. The Bush administration wants the House to approve a Senate bill that would in part have provided legal protections for telecommunications companies that helped the government wiretap U.S. computer and phone lines after the Sept. 11 attacks without approval first from a secret court.

McConnell said Sunday that without the legal protections, telecommunications companies are now unlikely to cooperate with the government in tracking suspected terrorists, and "we cannot do this mission without help and support from the private sector."

_Said intelligence officials have not located a terrorist cell inside the United States "that is directly associated with al-Qaida," but that al-Qaida remains viable because it has leadership, maintains a safe haven in Pakistan and is recruiting and training. Still, McConnell said al-Qaida is not as dangerous as it was before Sept. 11, 2001.

_Contended that the threat of Iran developing nuclear weapons has not changed much despite a U.S. intelligence report released in December that concluded Tehran halted its nuclear weapons ambitions in 2003. McConnell said Iran had terminated one aspect of a technical design but "they could have turned it back on now and we wouldn't necessarily know."

"They could do it by 2009 — unlikely," he said, referring to the ability to make a nuclear bomb. "The range is 2010 to 2015. And the best guess is about the middle range there for having a nuclear weapon."

McConnell spoke on "Fox News Sunday."