(CNSNews.com) – While Iran faces unprecedented sanctions for its nuclear activities, it has got off lightly over many years for its support for terrorism, experts told a congressional panel on Wednesday.

Iran, its Islamic Revolutionary Guard Corps’ external operations branch, Qods Force, and proxies like Hezbollah in Lebanon have for too long got away with carrying out devastating terror attacks around the world, including those targeting Americans, they said.

“The regime has paid a very low price for sponsorship of terrorist attacks from the Marine Barracks bombing in 1983 to the attacks last week,” said American Enterprise Institute scholar Danielle Pletka, referring to a suicide truck bombing in Beirut that killed 241 people, mostly U.S. Marines, and to last Wednesday’s suicide bombing in Bulgaria, which cost the lives of five Israeli tourists and a Bulgarian.

“It has hardly paid a price for flouting Security Council strictures on exporting weapons to Hezbollah,” Pletka continued. “It has never paid a price for the 1,000 U.S. servicemen’s lives taken by Iranian groups in Iraq.”

Pletka was testifying before a Senate Foreign Relations subcommittee on Near Eastern and South and Central Asian affairs hearing on “Iran’s support for terrorism in the Middle East.”

In his testimony, Washington Institute for Near East Policy senior fellow and counterterrorism specialist Matthew Levitt made a similar point.

“One reason Iran is using terrorism as an extension of its foreign policy is that it remains a cost-effective and relatively risk-free endeavor for Tehran,” he said. “Iran must be led to believe that the cost of sponsoring or carrying out an act of terrorism will now be high.

“That will be a difficult message to convey in the light of Iran’s history of carrying out massive attacks without any significant reaction from America, even in the case of attacks against U.S. interests,” Levitt added. He cited attacks in Beirut, Iraq and the 1996 bombing of the Khobar Towers in Saudi Arabia, in which 19 U.S. soldiers were killed.

Levitt and another expert, Daniel Byman of the Brookings Institution, both said the U.S. should urge allies to tighten up on Iranian diplomatic missions, reducing the numbers of personnel to the minimum needed for legitimate activities.

Iran has allegedly used embassies in support of militant activity for many years. Three of eight Iranians accused by Argentina of responsibility for the deadly 1994 bombing of a Jewish community center in Buenos Aires were attached to Iran’s embassy there. In 2007, Gen. David Petraeus told reporters that the Iranian ambassador in Baghdad was a Qods Force member.

The witnesses told the panel American’s allies should also be pressed to stop treating Hezbollah – which Pletka described as “the most lethal terror group in the world” – with kid gloves.

“Too often Hezbollah has got a free pass from U.S. allies because it also engages in political and social welfare activity, leading some states to try to distinguish between its ‘legitimate’ and ‘illegitimate’ sides,” said Byman.

Other recommendations for U.S. action included applying financial leverage.

“It Hezbollah wants to continue as Iran’s proxy, then aid to Lebanon needs to be reconsidered,” said Pletka. “If some among the Palestinians wish to continue to play footsie with Iran, then we, the Arabs, and the Europeans need to ensure that Iran is their only donor.”

Witnesses and lawmakers agreed that an Iran emboldened by a nuclear weapons capability would likely become an even more active sponsor of terrorism around the world that it is today.

“Even if it did not ever use an atom bomb, a nuclear Iran would feel empowered to conduct more terrorist attacks against U.S. and Israeli targets, provide more lethal assistance to Hezbollah and Palestinian militant groups, and give the Qods Force greater liberty to support terrorist groups across the Middle East,” said subcommittee chairman Sen. Bob Casey (D-Pa.) in his opening statement.

Byman also said a nuclear-capable Iran would likely give even greater support to groups like Hezbollah. Pointing to Pakistan as an example, he said once that country had developed nuclear arms – and a perceived degree of immunity against India’s more superior conventional forces – it stepped up its support for jihadist groups fighting Indian rule in disputed Kashmir.

Byman did, however, say he thought it unlikely that Iran would pass nuclear technology on to terrorist groups.

“One indication of Iran’s caution on this score is that it has not transferred much less-lethal weapons, such as chemical weapons, even though these have been in Iran’s arsenal for over 25 years.”

But one thing that could change that calculus, he said, would be if the Iranian regime believed itself to be facing the imminent threat of regime change, with “nothing to lose.”

Several witnesses referred to Shi’ite Iran’s relationship with the Sunni terrorist network al-Qaeda, despite their sectarian differences.

The U.S. Treasury Department last summer accused Iran of collaborating with an al-Qaeda network that sends money and recruits through Iranian territory in support of its activities in Iraq and Afghanistan. (copyright 1998-2012 Cybercast News Service 07/26/12)