January 18, 2007. Ardeshir Hassanpour, a nuclear physicist with extensive knowledge of Iran's nuclear program is found dead in his apartment.
Reva Bhalla, a senior analyst with the private intelligence firm Stratfor, believes the Israeli intelligence agency, Mossad, was behind his assassination.
"Hassanpour was someone that we deemed as critical to the program and would have been a likely target of an intelligence service like the Israeli Mossad," Bhalla said.
A month later in February. Ali Reza Asgari, a top general in Iran's elite Revolutionary Guards, disappears while on a trip to Istanbul, Turkey. Some believe that he defected to the United States.
Iran's Nuclear Sphinx
Meir Javedanfar is an Iranian-Israeli political analyst living in Tel Aviv. He's the author of The Nuclear Sphinx of Tehran.
"Ali Reza Asgari provided important information about Iran's nuclear program, especially about Iran's cooperation with Syria," Javedanfar said.
According to a former German Defense Ministry official, Asgari revealed details about Iran's financing of a covert nuclear arms program at the al-Kibar facility in Syria. The intel was passed on to the Israelis.
On the morning of September 6, 2007, seven months after Asgari's defection, Israeli F-15 fighter bombers dropped 22 rockets on the al-Kibar complex.
"This is another example of Israel trying to undercut each and every one of Iran's levers that it holds through militant proxies like Hamas, like Hezbollah, as well as within Iran itself," Bhalla said.
Then in June 2009, Shahram Amiri, another scientist working for Iran's nuclear agency went missing while on a pilgrimage to Saudi Arabia. Iran accuses the Saudis of kidnapping and turning him over to the United States.
It was shortly after Amiri's disappearance that the U.S. became aware of a secret nuclear facility near the Iranian city of Qom.
Israel's Shadow War
Alex Vatakan is an Iranian specialist working for Jane's Intelligence.
"Could it be a coincidence? Maybe, maybe not," Vatakan said. "But the fact is that these defections are a huge value to the Western intelligence community."
It's all part of what analysts say is Israel's attempt to decapitate Iran's nuclear program, overtly and covertly.
"And that really shouldn't surprise anyone," Bhalla said. "Israel doesn't have a whole lot of good options in trying to undermine the Iranian nuclear program. Trying to get military strike on its own is extremely difficult for Israel."
"So for the moment Israel engages in a shadow war against the Iranian rulers and their militant proxies across the Middle East."
"It's about the assassination of people working for the Iranian government in the Palestinian Authority, it's about the assassination of Hezbollah people with links to Iran," Javedanfar said. "It's about the assassination of Iranian nuclear scientists."
And the psychological warfare continues. On Tuesday morning, January 12, 2010, Masoud Ali Mohammadi, a nuclear physics professor, was on his way to work when a motorcycle parked outside his home in Tehran exploded killing him instantly.
Eight days later on January 20, some 760 miles away from Tehran, a 27-member plus hit team walks into this luxury hotel in Dubai and assassinates 49-year-old Mahmoud al-Mahbouh. Mr.al-Mahbouh was a senior Hamas leader allegedly involved in smuggling Iranian weapons into the Gaza Strip.
Both incidents have been blamed on the Israeli secret service.
"What we know for sure is that there's a psychological war being waged against the Iranian nuclear program where the death of a scientist, even if it were of natural causes, is made into something mysterious in order to create fear among Iran's nuclear scientists," Javedanfar said.
High Level Defections
And the current political turmoil in Iran is only adding to fears in Tehran of additional high-level defections.
"We are seeing people from different paths of life in Iran either leaving the country or staying within the country but leaving the state machinery in opposition to the policies being pursued by Mahmoud Ahmadinejad and other hardline figures in that country," Vatakan said.
Those policies are forcing the United States and other countries to consider tough new sanctions against Iran. The question now is whether covert or overt actions can stop the Iranians from going nuclear.
*Original broadcast March 6, 2010.