If that should be confirmed, it will likely be the first time that the Iran branch of the Islamist group has supported an attack or attempted attack in the West, according to Seth Jones, a security expert with the RAND Corp. think tank's International Security and Defence Policy Centre in Washington and the author of the 2012 book, Hunting in the Shadows: The Pursuit of al-Qaeda since 9/11.
At today's media conference, the RCMP said it did not have evidence that the Iranian government was involved, and Jones told CBC News that he would be surprised if Tehran was part of such a plot.
He also said he doubts the Iranian government was even aware of al-Qaeda in Iran's support for the accused plotters, identified by the RCMP as Chiheb Esseghaier, 30, of Montreal, and Raed Jaser, 35, of Toronto.
The two men are charged with "conspiring to carry out a terrorist attack against a VIA passenger train."
The Iran/al-Qaeda relationship
Al-Qaeda members arrived in Iran when the 2001 war forced them from their Taliban-sponsored base in Afghanistan. While some al-Qaeda leaders went east to Pakistan, others went west to Iran, including some of the group's most senior leaders, according to Jones who, until 2011, served with the U.S. Special Operations Command, including in Afghanistan.
He says that while the Iranian government at first facilitated al-Qaeda leaders fleeing to Iran, by early 2002 Iran had detained them under a form of house arrest.
Around the same time, Osama bin Laden had ordered al-Qaeda in Iran's so-called management council to provide "strategic support to the organization's leaders in Pakistan," Jones writes in a 2012 article for the journal Foreign Affairs. About the same time, Iranian and U.S. officials met, and the Americans demanded, unsuccessfully, that the al-Qaeda members be deported to their countries of origin.
While Jones says there has been co-operation between Iran and al-Qaeda, "the organization is no Iranian puppet."
However, the details of that relationship since 2003 remain hazy, he adds. Some al-Qaeda members and their families have been released from Iranian custody, but the management council remains under limited house arrest. Though its members have been allowed to raise funds and communicate with other al-Qaeda affiliates.
Moving money, fighters and weapons
"The vast majority of their work over the past several years appears to have been a transit of weapons, fighters and money and other kinds of material, but not actually operations, so this would be a marked departure from al-Qaeda operations in Iran," if the RCMP/FBI probe is correct, Jones said in an interview on Monday.
There is evidence the group has been somewhat involved in operations next door in Iraq, Jones says. But "they have gotten very clear messages from the Iranian regime not to conduct operational planning from Iranian territory because it would put pressure of the Iranian government."
The RCMP said its investigation, code-named Operation Smooth, began in August 2012.
Al-Qaeda members who have been in Iran include Osama bin Laden's son, who apparently left in 2009 and was killed soon after in Pakistan, as well as Osama's son-in-law, Sulaiman Abu Ghaith.
In a New York court room in March, Abu Gaith pleaded not guilty to plotting against Americans in his role as al-Qaeda's top spokesman since 2001.
Believed still in Iran are Yasin al-Suri, an al-Qaeda facilitator who has moved recruits and money from the Middle East to al-Qaeda in Pakistan, according to Jones, and Saif al-Adel, an Egyptian who once headed al-Qaeda's security committee.
Al-Adel also has a Canadian connection. In her book, Guantanamo's Child, Toronto Star reporter Michelle Shephard mentions that in 1998 al-Adel looked after Canadian teenager Abdurahman Khadr, Omar Khadr's brother, while their father was away.
Jones argues that "Iran is likely holding al-Qaeda leaders on its territory first as an act of defence. So long as Tehran has several leaders under its control, the group will likely refrain from attacking Iran," which is a Shia Muslim country, while al-Qaeda is Sunni Islamist group which has often targeted Shias.
On the other hand, should the U.S. or Israel attack Iran, "Tehran could employ al-Qaeda in a response," Jones has said.
If the Iranian government should be convinced that al-Qaeda in Iran was secretly involved in supporting a plot in Canada, Jones expects Tehran will detain or expel some of the individuals responsible. "I cannot imagine the Iranian government would be happy with al-Qaeda plotting from its soil," he told CBC News.