By Rob Watson BBC Washington correspondent

But only Iraq is facing the prospect of US military action.

We have no intention of invading North Korea. We expect North Korea to adhere to her obligations. She's in an agreement with the United States and said that she would not develop nuclear weapons. We expect people to keep their word President George Bush

So why is the Bush administration going so softly, softly on Pyongyang?

What a difference a year makes - just 12 months ago, President George W Bush lumped in North Korea with Iran and Iraq as part of the 'axis of evil'.

Today, he is ready to talk to Pyongyang - leaving many in Washington and the rest of the world wondering why North Korea gets kid gloves and Iraq the iron fist.

Diplomatic tools

The explanation offered by US Secretary of State Colin Powell is that Saddam Hussein is more menacing and North Korea more amenable to diplomatic pressure from such powerful neighbours as Russia and China.

"In the case of Iraq, it is not just the capability, it is an intent to use it and they have used it," Mr Powell said.

"In the case of North Korea, we address this trouble that they have nuclear weapons, but we think there are different sets of tools that can be used," he added.

North Korea was dubbed part of an 'axis of evil'

But many critics, like former President Jimmy Carter's national security advisor, Zbigniew Brzezinski, believe that is not the whole story.

"I think it's quite obvious that North Korea is a more difficult military problem than Iraq. It's much easier to deal with Iraq militarily than it is with North Korea," he said.

Military threat

The implication is that, paradoxically, the more of a threat you are militarily, the less likely you are to have Mr Bush sending troops your way.

"I hope that is not the strategic conclusion that would be reached from this problem. But certainly, it seems to be pointing in that direction, at least superficially," Dr Brzezinski says.

And though it has to be taken with a large pinch of partisan salt, senior Democrats, among them Senator Joe Biden, have been quick to suggest that maybe Mr Bush has got things the wrong way round.

In my view, if things get out of hand in North Korea, a lot more damage can be done to US interests than can be done in the near term in Iraq US Senator Joe Biden

"There is no urgency in Iraq - as long as the inspectors and the international community are there, there is little or no prospect of them being able to do much mischief," Mr Biden said.

"In my view, if things get out of hand in North Korea, a lot more damage can be done to US interests than can be done in the near term in Iraq," he added.

Redefining 'evil'

But the administration also has its defenders. The former US ambassador to Seoul, Donald Greig, says the best way to stop things getting out of hand is to opt for the kind of diplomacy now being used by the White House, though he says the president could have made life easier for himself.

"I think that the difficulty has arisen in part from the axis of evil rhetoric which makes the world think that we view North Korea, Iraq and Iran as more or less birds of a feather," Mr Greig explained.

"In fact, each is uniquely different from the other and I think that we are appropriately differentiating our approaches to the two countries," he added.

"But there has to be a little bit of explaining away of why the axis of evil didn't lock us into a sort of cookie cutter approach to foreign policy."

Of course, Bush administration officials say the axis of evil speech was never intended to suggest the cookie cutter or "one size fits all" approach to foreign policy.

The problem is that is exactly how it was seen by the rest of the world, whether it was meant to be or not.