Comments by Prime Minister Stephen Harper and Foreign Affairs Minister John Baird elaborated on a decision that caught many observers off-guard.
They cast the move as a security decision in remarks they made Friday, a day on which Western embassies came under attack in different parts of the Muslim world.
Baird said Canada has always been committed to the Iranian people despite its problems with their government but was concerned about Iran's unwillingness to help protect foreign embassies from attack.
That was a key factor in closing Canada's mission in Tehran a week ago, he said, a move that drew a rebuke from Iranian officials.
"We couldn't have possibly been clairvoyant enough to predict the upheaval going on around that region when we made the decision three or four weeks ago and then announced it 10 days ago," Baird said after a speech to an international relations group.
"But the one thing you see in Cairo, you see in Tunisia, you see in Benghazi and Tripoli, in Khartoum, is the governments and their security forces are doing what they can to protect these diplomatic installations. They don't do that in Tehran."
Baird said the federal government began re-revaluating its presence in Iran several months ago, especially after Iranian authorities did nothing to stop an incursion against the British embassy last November.
He said Iran's record of non-assistance to foreign embassies goes back decades. The most famous example came in 1979 when militants stormed the U.S. embassy during the Iranian revolution and took 52 people hostage for 444 days.
Canadian embassy staff actually helped some of the Americans flee the country in what has since famously become known as "The Canadian Caper." That episode is the focus of a new film, "Argo."
"Seven or eight months ago, we made the decision to draw down our staff. We ended the immigration program in Tehran," Baird said. "We went down to a skeletal staff of seven or eight."
A further step that played into the decision was Parliament's passage of the Justice For Victims of Terrorism Act, which requires Canada to list by Friday countries that are state sponsors of terrorism.
"Iran is clearly a state sponsor of terrorism," he said. "The facts are unequivocal in that regard.
"I don't know how you'd call a state a state sponsor of terrorism and then leave men and women on the ground there."
Baird also said there were concerns about the embassy building itself, saying it is not as safe as the government would like. He noted the facility sits next to the road.
"We spent a lot of time debating it and thinking about it but at the end of the day it just became uncomfortable to leave it open," he said.
"We made a difficult decision that I don't apologize for. We believe it was the right decision."
When the closure was announced, Iran's Fars news agency said the country's parliamentary speaker, Ali Larijani, cancelled a planned visit to Canada in protest.
Tehran's foreign ministry spokesman also accused the Harper government of "extremist" views and said it was "unwise'" for Canada to have set a five-day deadline for Iranian diplomats to leave the country.
The Iranian foreign ministry also said the embassy closure was "unprofessional, unconventional, and unjustifiable."
The Foreign Affairs Department has warned Canadians against travelling to Iran, singling out dual Canadian-Iranians as especially vulnerable because Tehran does not recognize their new citizenship.
Harper, at another event outside Montreal near the U.S. border, echoed Baird, saying Iran had a dismal record of respecting diplomatic immunity and it was vital the embassy staff be protected.
The prime minister expressed concern about the security of diplomats, given events in the Middle East, and he drew links to the Iran embassy closure.
"It's my responsibility to ensure that our people are protected," Harper said.
"Obviously we've closed one mission — that's in Iran — where we thought the risks are particularly high, mainly because the government in the past ... has not recognized diplomatic immunities and protections."
Canada also closed its embassy in Cairo on Thursday and will evaluate on a day-to-day basis when to reopen it.
"Obviously the security of our personnel is the top priority," Baird said.
"We're horrified with the violence we've seen but at least the state (of Egypt) is providing a modicum of support for the diplomatic community there."
Baird said Canada is not contemplating withdrawing embassy staff from Egypt at the current time.
In a broad speech on foreign policy Friday, Baird said Canada must play an active role in promoting fundamental liberties around the world even if it makes people uncomfortable.
He said discussing rights for women and gays and lesbians isn't always popular at international forums.
But the practice of forced marriages must end, he said, pointing out that when girls as young as nine years old are forced into marriage there's no chance they will be able to get an education.
He also discussed gay rights and told the story of Ugandan activist David Kato. The man was beaten to death in his home with a hammer after a tabloid newspaper called for his killing.
"It is cases like his that cause me to raise this issue, often to the discomfort of people sitting across the table, as I did at recent meetings in Australia and New York," Baird said.
"In these meetings, Canada was the loudest voice. I called on my counterparts to repeal regressive laws in their own countries because I firmly believe it is the role of the state to protect its people regardless of gender, sexuality or faith."
He insisted, however, that human rights and democracy are not something to be forced on others. All Canada can do is promote its values, he said.
"Doing what is right does not mean forcing our values on others," he said.
"We cannot impose our form of government or our institutions on others. Doing so assumes we need to teach people how to be free. We don't. We all share an inalienable right to be free. Our job is to help people understand this fundamental truth."
The foreign affairs minister reiterated several times during his appearance Friday that Canada is committed to the Middle East and has no problem with the Iranian people — only their government. Relations with them had been frustrating, he said.
"We've had little capacity to be able to interlock with the Iranian embassy," he said in a brief question-and-answer period. "Their support of international terrorism, their abysmal human-rights record, has made it very difficult for any Canadian government to effectively liaise with them."
Baird said while two Canadian citizens and one permanent resident who are on death row in Iran have the full support of the government, Canada is enlisting "friends and allies" to press their case with the Iranian government.
He said efforts by Canadian diplomats had been met "with nothing but hostility" and "outrageous comments."
"Frankly, our ability to influence the regime in Iran has been limited for some time," he said, pointing out that Canada had little impact when it came to pressing the country on the death of Zahra Kahzemi, an Iranian-Canadian photojournalist who was beaten to death in an Iranian prison in 2003.
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