Why did they do this? Diplomats from many countries have been asking this for days about Canada's sudden move to cut off diplomatic ties with Iran. Whether it was a good move or bad, there can be no doubt that in the execution Ottawa bobbled the ball.

If Prime Minister Stephen Harper and Foreign Affairs Minister John Baird wanted to deliver a clear message to the world about Iran, they didn't. Instead, they confused the world.

For many countries, Ottawa's basic message, "Iran is bad" was crossed with another signal: "Canada is weird."

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The Harper government was clearly fed up with Iran on many fronts and chose to dispense with stagnant diplomatic ties that it decided were just getting in the way of tougher criticism. But it made Canadian foreign policy look erratic by muddling the message.

For most foreign governments, the message is interpreted through their diplomats, and diplomatic language. To diplomats, breaking off relations – suspending them, technically – is a serious step, a notch below declaring war. Countries maintain diplomatic ties through cold wars and even hot skirmishes. For days, foreign diplomats have been seeking explanations from fellow diplomats, Canadian officials, even journalists. To them, it's shocking.

That doesn't mean Canada should only do things that won't shock foreign diplomats. But if Ottawa wants to send a message, it has to explain, not confuse. This time, the explanation has been vague and shifting.

For starters, there was the suddenness. On Friday, Mr. Baird went before a microphone in Vladivostok to announce the closing of Canada's embassy in Iran and the expulsion of Iranian diplomats from Canada. Okay, that's because the Canadian government wanted to get all its diplomats safely out of Tehran before it said anything and then Mr. Baird, at a summit in Russia, rushed to the microphone just after 1 a.m. local time.

But the scene led to a sense of urgency. The obvious question was, why now? Mr. Baird didn't offer a convincing answer. His first explanation was a long list of complaints about Iran's behaviour on human rights, its nuclear program and support for Syria – all legitimate but none new – and also that, given Iran's poor record for protecting diplomats, "it's simply no longer safe" to have Canadian representatives in Iran.

The lack of a strong explanation fuelled speculation. Some suggested Israel had tipped Ottawa off to an imminent military strike, so Mr. Baird has since made a point of repeatedly denying that. The CBC speculated Iranian diplomats here might have been organizing sleeper cells.

The real safety reasons, it turned out, were more pedestrian but poorly explained – a sense that Canadians in Tehran were exposed. There's no U.S. embassy there and the British left last November, when their gated embassy was stormed by protesters. Ottawa worried Canadians could be next in line as the enemy foreigners. If Israel launches strikes, Canadian diplomats believed they would be taken hostage. Ottawa, after all, has become Israel's staunchest defender.

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The Harper government also had a September deadline to list Iran as a "state sponsor of terrorism" under a new law, and worried about retaliation. It will probably also soon impose sanctions on Iran's powerful Revolutionary Guards. There was one other thing Ottawa didn't adequately explain: its diplomatic relations had become less than zero because Iranian officials wouldn't meet Canadians.

But that's still not the whole reason for the Harper government's actions. It didn't have to expel all Iranian diplomats to deal with safety concerns in Tehran. On Monday, Immigration Minister Jason Kenney offered a new reason: Iranian diplomats were intimidating Iranian-Canadians.

But the key reason, certainly, was that the government wanted to make it part of a statement about Iran as a rogue nation. That's why Ottawa listed Iran as a state sponsor of terrorism on the same day as it made its surprise announcement.

It's a statement that confused, because Mr. Baird didn't offer a systematic explanation that cutting off diplomatic ties was not decided suddenly. The Harper government failed to grasp that the world would expect a clearer rationale for a big step.

After all, if you're trying to send the world a strong message about Iran, it's best not to leave them puzzled about Canada.