Talk of a war between the U.S. and Iran has intensified after U.S. President Donald Trump's National Security Adviser John Bolton announced this month the deployment of war planes to the region.

The move is a response to reported signals that Iran has been loading missiles onto ships in the Persian Gulf.

Bolton has been calling for the U.S. to bomb Iran for years. Critics fear that his recent rhetoric will intensify an already fragile situation.

David Frum is one of those critics. Currently a staff writer at The Atlantic magazine, Frum was a vocal supporter of the 2003 U.S.-led invasion of Iraq. As President George W. Bush's speech writer, he helped pen the famous "Axis of Evil" speech, which excoriated Iraq and North Korea, but also Iran.

A photo from Thursday, May 16, shows the U.S. Navy launching an F-18 Super Hornet from the deck of the USS Abraham Lincoln aircraft carrier in the Arabian Sea. On Saturday, diplomats warned that commercial airliners flying over the wider Persian Gulf faced a risk of being 'misidentified' amid heightened tensions between the U.S. and Iran. (U.S. Navy/Associated Press)

But he has since expressed regret for supporting that invasion. He also says that any war with Iran will be an even bigger, more destructive mistake than the Iraq debacle.

He sat down with Wendy Mesley, the host of CBC's The Weekly with Wendy Mesley, to explain why invading Iran would be a bad idea. You can watch the full interview above.

You supported at the time the invasion of Iraq, but now you're writing that if the Iraq war is repeated in Iran, that it would terrify you. What's so terrifying?

DF: Well let's look at the difference in the process. With the Iraq war, George W. Bush put in place a lot of important pieces. He had an operating war plan.

And with all that, it was still less than a complete success, to put it mildly. Now what if you don't do any of those things?

You're going to try to change the regime there with no plan to do it.

So you have said that this is so crazy, that you can't figure out what is going on in the Trump administration if it is considering this. What is going on?

DF: Well it looks a lot like a bluff. No one has seen the evidence for what they are warning about, but they are huffing and puffing.

So there is a real possibility here that they're just making threats without any plan to follow up.

But the problem is sometimes if you play cards and you make a bluff, the bluff gets called.

Former George W. Bush speechwriter and author of Trumpocracy: The Corruption of the American Republic, David Frum, is seen here in a 2018 CBC News interview. (Evan Mitsui/CBCNews) (Evan Mitsui/CBC)

Are we on a path for war? I mean Donald Trump was asked, "Is there a war coming?" And he says, "I hope not." What's your sense?

Trump likes this idea of himself as an unpredictable figure, but it's very important for superpowers to be very predictable.

Because Trump doesn't give the Iranians a path away from conflict, he's in danger of walking himself down a path to conflict without ever knowing where he's going.

It's hard to read the tea leaves here, but it sounds like the military, the White House, and everybody else is divided over this. What's your sense?

DF: Well a lot of the people in the military are trying to alert friendly reporters this is all vaporware. No one's told us that we're supposed to be doing anything. No one's giving us any instructions.

So there's a discrepancy between the highly aggressive rhetoric that comes from the administration and some of its supporters in Congress, versus the actual work that is being done to be prepared for the worst to happen.

But that's the kind of gap into which trouble can step.

Where should Canada be now? What should it do?

DF: Well, one thing I think that any self-respecting Canadian government is going to want to do is to say to the Americans, "If you want our support, you have to ask for it."

You can't just demand it. You can't just threaten.

And that has been a real problem with the Trump administration. They don't ask allies to obtain that freely given buy-in that's been so crucial to American success.

(Answers have been edited for length and clarity.)