The head of the U.S. Senate Homeland Security committee says he believes Iran is behind cyberattacks this week on U.S. banks.

In an interview with U.S. television network C-SPAN, Senator Joseph Lieberman said he thinks the disruptions of the websites of JPMorgan Chase and Bank of America were carried out by Iran and its Quds Force, a unit of its elite Revolutionary Guards. He said he does not believe these were “just hackers.”

Lieberman said he believes the attacks were a response to “increasingly strong” economic sanctions that the U.S. and its European allies have put on Iranian financial institutions.

The United States and several other Western countries have united to impose sanctions on Iran over its nuclear program, which they suspect is aimed at developing nuclear weapons. Iran insists its uranium enrichment program is solely for peaceful purposes.

On Saturday, the U.S. Senate almost unanimously passed a non-binding resolution opposing Iran's development of atomic weapons.

The Senate passed the measure in a vote of 90 to 1.

The wording of the non-binding measure specifically states that the measure should not be interpreted as an authorization for the use of military force or a declaration of war.

Republican Senator Rand Paul , who cast the lone “no” vote, has denounced the resolution as an excuse for the use of military force.

The Obama administration has resisted Israeli calls to set a deadline for Iran to stop work on its nuclear program.

Israel sees a nuclear armed Iran as a threat to its existence, and refuses to rule out military action against Iranian nuclear sites.