For, although the almost routine report of the execution on Tehran radio referred only to three of the accused "passing military information in time of war to the CIA" it did not reveal that all four men were Iranians. Three were officers in the Iranian army and the fourth a member of the Iranian Revolutionary Guards.
All four, according to a source close to Iranian authorities, had been spying for Iraq since almost the start of the 1980-88 Iran-Iraq war, and had sold their country's secrets for money. In Iranian eyes, there is now little or no difference between the Iraqi-backed Mujahedin Qalq and the CIA; and Tehran's announcement last month that a $20m (pounds 13m) budget had been approved "to uncover and neutralise US government conspiracies" means that the intelligence war between the Iranian regime and its violent opponents is likely to get hotter in the coming months.
Iranian sources maintain that only those who oppose Tehran "militarily" - with bombs - or at the behest of Western intelligence services are targeted. Thus two members of the mujahedin living in Baghdad - Ifat Haddad, a member of the National Council of the Iranian resistance, and Fereshta Essendiani - were killed in an ambush by Iranian agents inside Iraq three weeks ago. Around 4,500 guerrillas, most of them Iranians, live in military camps in Iraq, armed and trained by Saddam Hussein's security services. The best known of Iran's victims, Shahpour Bakhtiar, the Shah's last prime minister and an activist in the struggle to overthrow the Islamic Republic, was knifed to death at his Paris apartment in 1991.
The most recent assassination of an Iranian in Paris, however, came only last month. Reza Mazlouman, who was a minister under the Shah, was shot twice in the chest and once in the head in a seventh-floor apartment in the suburb of Creteil. Abolhassan Bani Sadr, an early post-revolutionary dissident and former president - whom the Iranian regime's supporters claim has never been targeted - claimed that although Mazlouman had been involved in "exiled monarchist movements", he had not recently been politically active, adding that he blamed Iran for the murder. It was the eighth assassination of its kind in Paris in recent years. Other dissident deaths have occurred in Europe and the Middle East.
Taha Kermanj, an Iranian activist in Turkey, was killed in January 1994, while Abu Bakir Hedayati, another opposition militant, was severely wounded by a letter bomb at his Swedish home in the same month. A Turkish group, the Islamic Action Organisation, has been accused by Turkish police of kidnapping a mujahedin officer, Ali Akbar Gorbani, who was handed over to Iranian intelligence officers for execution in 1992, and of drawing up an intelligence report for the Iranian security services on the opposition activist Abbas Golizade, who was abducted later the same year.
The Iranian security services' belief that the US actively wishes to destabilise the regime is not simply xenophobia. Just over a year ago, the CIA officially asked the US government for $19m to continue covert operations against Iran and Iraq. Much of the money, according to a report in the New York Times, was "intended to finance secret programmes to sabotage or gather intelligence about dangerous weapons programmes... terrorist groups and activities and drug trafficking..." Tehran suspects that some of this money is being used not against President Saddam, but to encourage his supporters to help the Iranian mujahedin.
"The violent opposition are dangerous now because they are without hope," the Iranian source says. "This is very serious. When a fatwa is given against a man who tries to overthrow the Islamic Republic with arms or through intelligence networks, the execution order is never rescinded. Even after they failed to kill Bakhtiar in an earlier assassination attempt, the fatwa continued until he was killed in 1991."
Amnesty International - dismissed by Tehran as "an instrument of the United States that is ready to use all means to put pressure on Iran" - says that thousands of opponents of the regime have been executed in Iranian prisons since the 1979 revolution. If these abuses of human rights have fallen in number recently, the war between Iran and its militant exiles is set to continue for months or years to come. Iranian security services are convinced, for example, that the hijacking of an Iran Air passenger jet to Israel represented - however unlikely it may seem - a relationship between Mossad and the Iraqi-backed mujahedin. Nor have they forgotten that mujahedin representatives have in the past met with US officials in Washington.
Iranian sources believe the mujahedin originally received assistance from France, and that Paris was at first encouraged to help the Iranian opposition by - of all people - Yasser Arafat. They claim that the relationship began after a meeting in Paris between a mujahedin representative from Baghdad, the then head of the French intelligence services, Alexandre Demaranches, and Hani el-Hassan, one of Mr Arafat's top PLO aides. Mr Demaranches, the sources say, regularly flew to Baghdad himself and, so they claim, was instrumental in arranging the extraordinary loan to Iraq of Super-Etendard fighters which Iraqi pilots used to fire Exocet missiles at Iranian oil tankers during the 1980-88 war.
Even Lebanon was concerned recently when an Iraqi-born Iranian and opponent of the regime, Abdul Wahab Ali Zaghi, was wounded by gunmen in Beirut's southern suburbs and taken to a government hospital at Baabda. While he was there, an Iranian in a car bearing diplomatic plates tried to have him removed into his "safe-keeping"; only when Mr Ali Zaghi objected did the Lebanese authorities realise that the car came from the Iranian embassy.
Iranian sources claim that the wounded man was involved in a private money dispute and that the affair had no political connections. The Beirut government was worried enough, however, to have him transported under military protection to a hospital north of Beirut. Not surprisingly, perhaps, he remains in the company of armed guards.