Director of National Intelligence Mike McConnell said the United States is still reviewing the case following the death of the top Hizbullah commander in a car bombing in the Syrian capital of Damascus.
Hizbullah 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 US against synagogues and other potential Jewish targets.
'It is a serious threat'
McConnell said he considers the threat to be primarily against Israel. But he said US intelligence officials are keeping close watch and taking any necessary action to protect the United States because Mugniyah has been
"responsible for more deaths of Americans and Israelis than any other terrorist with the exception of Osama bin Laden."
"It is a serious threat," McConnell said. "There's some evidence it may have been internal Hizbullah, it may have been Syria. We don't know yet."
On Sunday, Defense Minister Ehud Barak said: "I don't believe that Syria, Hizbullah and Iran have any idea of who did it. However, Hizbullah has decided – as we saw in Nasrallah's speech – to point an accusatory finger at Israel.
"Because of this, we must assume that Hizbullah will attempt to respond (with an attack) in Israel or abroad. It is possible they will do so with the help of Syria or Iran," Barak said.