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Nuclear killing: Is West waging 'covert war' against Iran?

The Obama administration is denying any role in the killing of an Iranian university professor working at a key nuclear facility. NBC's Richard Engel reports.

Story updated 3 a.m. ET:

The Obama administration denied any role in the assassination on Wednesday of an Iranian nuclear scientist, in response to suspicion that Israel or the United States were involved in the attack - and similar previous incidents.

Nuclear scientist Mostafa Ahmadi Roshan, 32, was killed Wednesday by a magnetic bomb reportedly attached to his car by two assailants on a motorcycle in traffic. The cars of three other Iranian scientists, at least two of whom were working on nuclear activities, were blown up in 2010 and 2011 in similar circumstances.

Iran, and many analysts in the region, suspect outside involvement in the incidents.

"Instead of actually fighting a conventional war, Western powers and their allies appear to be relying on covert war tactics to try to delay and degrade Iran's nuclear advancement," said Theodore Karasik, a security expert at the Dubai-based Institute for Near East and Gulf Military Analysis.

But the U.S. has insisted it had nothing to do with Wednesday's killing.

Iranian Vice President Mohammad Reza Rahimi, in charge while President Mahmoud Ahmadinejad travels in Latin America, told state television that "this terrorist act was carried out by agents of the Zionist regime (Israel) and by those who claim to be combating terrorism (the United States) with the aim of stopping our scientists from serving" Iran.

He said Iran's nuclear program would go on.

Iran has said it is developing nuclear capabilities only for energy and other peaceful purposes, but the United States and its allies accuse it of wanting to create a nuclear weapon. Four rounds of sanctions have been imposed on Iran. On Jan. 23, European Union foreign ministers plan to discuss a possible oil export embargo, adding further pressure.

Iran urged the U.N. Security Council and Secretary-General Ban Ki-moon to condemn the assassinations of scientists, calling the killings "cruel, inhumane and criminal acts of terrorism." Iran's U.N. Ambassador Mohammad Khazaee appealed to Ban and the 15-nation council, "Any kind of political and economic pressures or terrorist attacks targeting the Iranian nuclear scientists, could not prevent our nation in exercising this right" to pursue its nuclear program, Khazaee said in a letter obtained by Reuters.

'Unnatural' happenings
The Obama administration denied any U.S. involvement. Israel did not deny involvement, and there are hints that the Jewish state at least had advance knowledge. 

The Associated Press reported that  Lt. Gen. Benny Gantz told a closed meeting of Israel's Foreign Affairs and Defense Committee on Tuesday that "2012 is expected to be a critical year for Iran." He cited "the confluence of efforts to advance the nuclear program, internal leadership changes, continued international pressure and things that happen to it unnaturally."

Gantz's testimony was leaked by a meeting participant who spoke on condition of anonymity.

On Wednesday, Israel's chief military spokesman, Brig. Gen. Yoav Mordechai, posted on Facebook: "I don't know who settled the score with the Iranian scientist, but I certainly am not shedding a tear," according to a Reuters report.

Hazhir Teimourian, an Iran expert at the Limehouse Group of Analysts in London, stressed to Reuters that it was impossible to be certain who carried out the attack. But he said Israel was a logical candidate.

"The Israelis really have the ability and the incentive," he said.

List of attacks
Iran has accused the Mossad, the CIA and Britain's spy agency of engaging in an underground campaign against nuclear-related targets, including at least four killings since early 2007. They include:

  • In January 2010, a physics professor, Massoud Ali Mohammadi, was killed by a bomb in a motorcycle that blew up near his car as he left his Tehran home for work.
  • In November 2010, scientist Majid Shahriari, who managed a "major project" for Iran's Atomic Energy Organization was killed and colleague Fereydoon Abbasi, on the U.N. Security Council’s sanctions list for ties to the Iranian nuclear effort, was wounded when motorcyclists attached magnetized bombs to their cars in separate parts of Tehran.
  • In July 2011, Darioush Rezaeinejad, who allegedly was working on a nuclear detonator, was shot in the neck outside his daughter's Tehran kindergarten.
  • In 2007, nuclear scientist Ardeshir Hosseinpour died of gas poisoning.

Another key attack was the release of a malicious computer virus known as Stuxnet in 2010 that temporarily disrupted controls of some Iranian centrifuges — a key component in nuclear fuel production.

Ronen Bergman, an investigative journalist with the Yediot Ahronot daily and expert on Israeli intelligence affairs, said the Mossad has "for years" targeted enemies that include "nuclear proliferators."

"The outcome of such assassinations are the actual neutralization of the main scientists and the intimidation of those left behind," he said.

Israel measures the gains in terms of the delays they cause Iranians.

"They are not keeping to the schedules they would like to keep to," former Mossad spymaster Meir Dagan said in a recent television interview, smilingly crediting the apparent sabotage spree to "God, who controls everything."

It also provokes panic in surviving colleagues, said an Israel official, generating a phenomenon that Mossad veterans dub "virtual defection."

"It's not that we've been seeing mass resignations, but rather a sense of spreading paranoia given the degree to which their security has been compromised," the official, who has extensive Iran expertise, told Reuters.

"It means they have to take more precautions, including, perhaps, being a little less keen to stand out for excellence in their nuclear work. That slows things down."

Israeli attacks
Israel has an admitted history of state-sponsored assassination and intimidation, from letter-bombs it sent German scientists serving Egypt's missile program in the 1960s to the Mossad hunt, using guns and booby-traps, for Palestinians involved in killing 11 Israeli athletes at the 1972 Olympics.

More recently, Israeli air-launched missiles and special forces picked off Palestinian uprising leaders. In 1995, motorbike-borne gunmen killed Islamic Jihad chief Fathi Shiqaqi in Malta, and another suspected Mossad team smothered Hamas commander Mahmoud al-Mabhouh in his Dubai hotel in 2010.

Proponents of such tactics say they stave off more ruinous open war and few voices are raised in Israel in condemnation. Mabhouh had helped smuggle rockets to Palestinians, a threat Israel cited in justifying its 2008-2009 offensive on the Gaza Strip, amid international outcry at the high civilian toll.

Also on Wednesday:

Clinton cites danger: Secretary of State Hillary Rodham Clinton, reiterating that the U.S. played no role in the killing of Roshan, said the United States is looking for an international understanding with Iran that ends its uranium enrichment program.called recent Iranian threats to close off the Persian Gulf "provocative and dangerous." She said the U.S. was committed to keeping the international waterway open. She called it "part of the lifeline that keeps oil and gas moving around the world." About 35 percent of the world's seaborne traded oil passes through the Strait of Hormuz. 

Slammed at the U.N.: France, Britain, Germany and the United States on Wednesday took advantage of a closed-door meeting of the U.N. Security Council to condemn Iran's decision to begin enriching uranium at an underground bunker. "It's a worrying development," French Deputy Ambassador Martin Briens told reporters. He added that Tehran's new move was a violation of multiple resolutions of the U.N. Security Council and the International Atomic Energy Agency's board of governors. "We see this as a step of escalation by ... Iran," Deputy German Ambassador Miguel Berger said.

Cuba visit: Iranian President Mahmoud Ahmadinejad arrived in Havana for a one-day visit. Reuters reported that Ahmadinejad was greeted by one of Cuba's vice presidents, Esteban Lazo, and was driven away in a black Mercedes ahead of a meeting with President Raul Castro. Cuba was his third stop on a Latin American tour meant to show support from four leftist-led nations - Venezuela, Nicaragua, Cuba and Ecuador -- as Iran is increasingly isolated by tightening Western economic sanctions over its uclear program.

Reuters, The Associated Press, The New York Times and msnbc.com's Jim Gold contributed to this article.

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