Here is a test for news junkies: On Oct. 21, Iranian nuclear negotiators left Vienna after negotiations with the United Nations, Russia, France and the United States. In their briefcases they carried a proposal requiring authorization from their government. The deadline for approval was Friday, Oct. 23. When the deadline came, what did Iran say?

A. Yes

B. No

C. Talk to you later.

Anyone who has followed the now 7-year-old effort by the international community to stop Iran's nuclear march could have predicted the outcome. There was no answer. Iran continues to confound and delay and outmaneuver. We could also predict what will come later. Iran never says Yes or No, except when it says Yes and No. And when it finally agrees to some watered-down compromise, it fails to keep its commitments.

Iran said it would answer a few days later, while prominent Iranians offered contradictory opinions about the proposal. The proposal offered little to get very excited about. Despite the breathless reportage describing it as a breakthrough, the plan was important mainly as a test; a test of a new attitude from Tehran and the effectiveness of President Obama's engagement strategy.

The substance of the deal ignored the centerpiece of the problem: Iran's continued nuclear enrichment in violation of international demands that it stop. The plan says nothing about ongoing uranium enrichment that Western nations believe aims for nuclear weapons.

Instead, it focuses on how Iran will obtain fuel for a medical research reactor, proposing that it send about 70 percent of its low-enriched stockpiles to Russia and France, which would enrich it to the level required for the reactor and ship it back to Iran. All the while, Iran centrifuges would continue spinning. Experts say the scheme could delay nuclear weapons production by a year, but we don't really know what exactly Iran already has in place.

The West wants Iran to send the full 70 percent in one shipment to Russia by the end of the year. Let's see how this cat and mouse game proceeds. Iran's main goal is to keep the conversation going as long as possible, doing exactly what French President Nicolas Sarkozy warned against: "gain(ing) time while the motors are running."

Tehran today is off balance, but Washington's engagement policy is not the reason. The country is profoundly divided. Until recently the regime appeared unshakeable. Now it seems to stand on a soggy foundation. The hardliners may keep control, but they have to watch their flanks. The Islamic Republic now faces a crisis of legitimacy after a stolen election. Political divisions have weakened the government, and ethnic divisions are giving it more reasons for concern. This is the time when tough negotiations could bear fruit, because Iran's government can ill afford more challenges to its hold on power.

The Obama administration's engagement policy will work only if the West acts firmly. Iran does not want tough sanctions, and it will try, as it has, to delay, confuse and backtrack.

It already ignored one deadline; one meant merely as a test of its intentions. Iran failed its test. Washington should not delude itself into thinking the delay was a sign of progress; quite the opposite.

If Obama wants results, let's hope this is the last missed deadline Tehran ignores and Washington celebrates.