Literally people who betray their country practice treason. In the history of Iran as well as many other nations there were a lot of traitors who sold out their nation to enemies for low prices. Shahram Amiri was an Iranian nuclear expert who was sentenced to death by Islamic Republic because he had sold classified information on the Iranian nuclear program to the United States. Amiri was executed but the payroll of the enemies of Iran contains a large number of names of which the most notable one is the Mujahedin Khalq Organization (the MKO/ the Cult of Rajavi).
A traitor to his country ranges from fifth “columnists” who are sympathetic to or working with the enemy to “spies” who work directly for the enemy. A traitor can also be merely sympathetic to the goals of the enemy, in this case it is called “bed fellow” or “fellow traveler”. He can also be naively fooled by the enemy’s propaganda into promoting the enemy’s goals. In this case, it is called “useful idiot”. Traitors can also be used as a proxy force by the enemies of their hometown. Regarding the MKO’s history, the group has played all parts of a traitor that were discussed here.
During the eight year of Iran-Iraq war, the MKO betrayed Iran as a fifth columnist, a spy and a proxy force. Ann Khodabandeh, former member of the MKO, correctly labels the group as “Saddam’s Private Army”. Massoud Rajavi directly worked for Saddam Hussein. He used to call Iraqi dictator, “the Land lord”. In exchange for the military and financial support by Iraqi Baath regime, the MKO provided them with classified intelligence on Iran and pleased them with cross border attacks against Iranian civilians and soldiers.
After the collapse of the Iraqi dictator in 2003, the MKO turned out to play other roles of a traitor. “The M.E.K.’s ties with Western intelligence deepened after the fall of the Iraqi regime in 2003”, write Seymour Hersh, the prominent American Journalist. 
Seymour Hersh reveals that the MKO agents received military and intelligence training in the US territory in 2005. His article “Our men in Iran” was published in the New Yorker in April 2012. According to the investigated article, the Joint Special Operations Command (JSOC) conducted training the MKO in Nevada desert and mountainous areas. Hersh quotes Robert Baer, a retired C.I.A. agent who is fluent in Arabic and had worked undercover in Kurdistan and throughout the Middle East in his career, “They wanted me to help the M.E.K. collect intelligence on Iran’s nuclear program.” Baer recalled,“They thought I knew Farsi, which I did not. I said I’d get back to them, but never did.” 
In a separate interview, a retired four-star general, who has advised the Bush and Obama Administrations on national-security issues, told Hersh that he had been privately briefed in 2005 about the training of Iranians associated with the MKO in Nevada by an American involved in the program. They got “the standard training,” he told Hersh, “in commo, crypto [cryptography], small-unit tactics, and weaponry—that went on for six months.” 
Hersh’s article was published just a few months after the NBC News reported that the assassination of the Iranian nuclear scientists was a team work by the MKO and the Israeli Intelligence Mossad. According to Richard Engel and Robert Windrem on the NBC News, “Deadly attacks on Iranian nuclear scientists are being carried out by an Iranian dissident group that is financed, trained and armed by Israel’s secret service, U.S. officials tell NBC News, confirming charges leveled by Iran’s leaders.” 
The MKO’s sympathy for the goals of anti-Iran figures in the US government, particularly the GOP leaders is widely covered by the journalists. The NBC News covers the bed fellowship too, “at least two GOP presidential candidates have no problem with the targeting of nuclear scientists. In a November debate, former House Speaker Newt Gingrich endorsed “taking out their scientists,” and former Pennsylvania Sen. Rick Santorum called it, ”a wonderful thing.” 
“The MEK’s opposition to the Iranian government also has recently earned it both plaudits and support from an odd mix of political bedfellows,” reported NBC News. 
Philip Giraldi, a former CIA officer who is contributing editor to The American Conservative and executive director of the Council for the National Interest denounces American sponsors of the MKO in his piece titled “The MEK’s Useful Idiots” on Antiwar.com. 
He writes: “The U.S. military and the CIA have in the past recruited MEK agents to enter Iran and report on nuclear facilities. Other MEK agents, recruited and trained by Israel’s Mossad intelligence agency, have recently killed a number of Iranian nuclear scientists and officials. The group appears to have ample financial resources, and it is generally believed that at least some of the money comes from Mossad. The MEK is able to place full-page ads in major U.S. newspapers and is also known to pay hefty speaker’s fees to major political figures who are willing to speak publicly on its behalf. The group claims to want regime-change in Iran to restore democracy to the country, an odd assertion as it itself has no internal democracy.” 
Giraldi believes that Zionist Americans are actually fooled by the propaganda launched by the MKO against the Islamic Republic. “Because the MEK is a resource being used by Israel in its clandestine war against Iran, it is perhaps inevitable that many friends of Israel in the United States are campaigning vigorously to have the group removed from the terrorism list, he asserts. “Indeed, neocons at their various think-tanks and publications as well as AIPAC all support delisting the group.” 
Given many evidences, investigations and testimonies, the MKO has committed the most treasonous acts against its own nation. The irony is that the group’s propaganda condemns the execution of Amiri as a criminal act and denies that it has cooperated with Israel for the assassination of several Iranian nuclear scientist. Possibly, the MKO claims that all the above mentioned references and many other that were not cited in this piece are agents of the Iranian Intelligence Ministry.
By Mazda Parsi
Hersh, Seymour, Our Men in Iran?, The New Yorker , April 5, 2012
 Engel, Richard & Windrem, Robert, Israel teams with terror group to kill Iran’s nuclear scientists, U.S. officials tell NBC News, NBC News, Feb 9, 2012
 Giraldi, Philip, The MEK’s Useful Idiots , Antiwar.com, March 08, 2012