I think Gates said it well today:

New U.S. Nuclear Policy Sends ‘Strong Message’ To Iran, North Korea, Officials Say

“I actually think that the NPR [review] has a very strong message for both Iran and North Korea,” Secretary of Defense Robert Gates said. “We essentially carve out states like Iran and North Korea that are not in compliance with NPT.”

The message to these countries, Gates said, “is that if you’re going to play by the rules … then we will undertake certain obligations to you. But if you’re not going to play by the rules, then all options are on the table.”

Gates told reporters the United States will “hold accountable” terrorist states despite the new policy and will continue to go after terrorists who want to acquire weapons of mass destruction.

There is also the caveat that the United States can revisit the policies if circumstances change.

“The United States reserves the right to make any adjustment to this policy,” he said. “We also recognize the real world we continue to live in.”

There you have it: The United States reserves the right to make any adjustment to this policy.