Over the weekend, responding to criticisms from Bush and McCain, Barack Obama explained his perspective on diplomacy.

This strikes me as the kind of sentiment that’s hard to disagree with, but John McCain spoke in Chicago this morning, and went after Obama for saying the potential threat posed by Iran is “tiny” compared to the USSR during the Cold War.

McCain said, “Obviously, Iran isn’t a superpower and doesn’t possess the military power the Soviet Union had. But that does not mean that the threat posed by Iran is insignificant.” McCain went on to argue that Iran is playing a destructive role in Iraq and is “intent on acquiring nuclear weapons.” McCain concluded, “They might not be a superpower, but the threat the government of Iran poses is anything but ‘tiny.’”

Does McCain really want to debate this?

First, Obama didn’t say the possible Iranian threat is “tiny.” He said it’s “tiny” when compared to the Soviet Union. As Josh Marshall explained, Russia was, after all, “the world’s greatest land military power, with a massive strategic nuclear capacity that carried on a multi-decade ideological struggle” with the United States. McCain thinks it reflects poor “judgment” to recognize the obvious difference between a nuclear superpower and Iran?

Second, there’s a bit of a contradiction here. Over the weekend, the McCain campaign said Obama was giving Iran too much credit, offering Iran “the status of a super power akin to the Soviets.” Today, the McCain campaign said Obama isn’t giving Iran enough credit. These guys should probably coordinate talking points among themselves before going on the attack.

And finally, on the substance, Obama is so obviously right about Iran it’s hard to believe this discussion is actually happening. As Newsweek’s Fareed Zakaria explained a few months ago: “Iran has an economy the size of Finland’s and an annual defense budget of around $4.8 billion. It has not invaded a country since the late 18th century…. Israel and every Arab country (except Syria and Iraq) are quietly or actively allied against Iran. And yet we are to believe that Tehran is about to overturn the international system and replace it with an Islamo-fascist order? What planet are we on?”

Ultimately, McCain seems to believe diplomacy just isn’t worth it. We could engage Iranians directly, but Iran might, as a result, get stronger, and our discussions may not stem the country’s ambitions.

Here’s the thing: thanks to the war in Iraq that McCain is so fond of, Iran is already getting stronger and more ambitious. So why keep pursuing an approach that isn’t producing the results we want?