SLAMABAD, Pakistan — President Bush has been searching vainly for Osama bin Laden for three years now, so I've decided to help him out. I'm traveling through Pakistan and Afghanistan to see whether I can find Osama, bring him back in my luggage and claim that $25 million reward.

So for the last few days, I've been peering into mosques and down village wells, even under mullahs' couches. No luck so far, but I did find something almost as interesting.

I'm talking about the arrangement under which the U.S. cuts Pakistan some slack on nuclear proliferation, in exchange for President Pervez Musharraf's joining aggressively in the hunt for Osama - in the hope of catching him by Nov. 2.

If a nuclear weapon destroys the U.S. Capitol in coming years, it will probably be based in part on Pakistani technology. The biggest challenge to civilization in recent years came not from Osama or Saddam Hussein but from Abdul Qadeer Khan, the father of Pakistan's atomic bomb. Dr. Khan definitely sold nuclear technology to Iran, North Korea and Libya, and, officials believe, to several more nations as well.

But, amazingly, eight months after Dr. Khan publicly confessed, we still don't know who the rest of his customers were. Mr. Musharraf acknowledged as much in an interview.

"I can't say surely that we have unearthed everything that he's done, but I think we have unearthed most of what he's done," Mr. Musharraf said. Translated, that means: I'm afraid you're eventually going to find out about other transactions that we're still trying to hide.

American intelligence experts haven't been able to interrogate Dr. Khan, and Mr. Musharraf claims that the U.S. has not even asked to do so. "Let me put the record straight: nobody asked us to be allowed to question him," Mr. Musharraf said.

President Bush apparently did not ask for that direct access at his meeting on Wednesday with Mr. Musharraf, and it's clear that the administration is not pressing the issue. Why? Because Mr. Bush in this election season has another priority: getting Mr. Musharraf to help catch Osama.

Unless he's pressed hard, Mr. Musharraf won't make Dr. Khan available. Dr. Khan is a Pakistani hero, and there'd be great outrage if so-called Yankee anti-Muslim crusaders were allowed to interrogate him. "There would be a very strong reaction," warned Ghafoor Ahmad, a senator and Islamic politician.

An interview with Senator Ahmad is a reminder that the alternatives to Mr. Musharraf could be worse: Mr. Ahmad indignantly told me that Osama had nothing to do with 9/11. He suggested that it might have been a joint operation of the U.S. government and Mossad.

So which other countries would Dr. Khan implicate if we could interrogate him?

Mr. Musharraf confirmed that the Saudi defense minister had visited Dr. Khan's laboratories a few years ago, but he insisted that Saudi Arabia was not a nuclear customer. I'm not so sure.

The Saudis, alarmed by Iran's bomb program and jealous of Israel's, may well want their own nukes. But if the Saudis build a bomb, so will Egypt, and all hell will break loose in the Middle East.

Mr. Musharraf also denied that Syria was one of Dr. Khan's clients. A Syria with nukes would also not be a prescription for stability in the Middle East. In addition, Dr. Khan had ties with African countries, and those ties are not yet fully understood.

The charitable explanation for Mr. Bush's failure to get to the bottom of the Khan affair is that putting too much pressure on Mr. Musharraf would risk his destruction in the crucible of Pakistani nationalism. And the U.S. government certainly has a genuine interest in catching Osama as soon as it can.

Yet it's impossible to overstate the risks if countries like Saudi Arabia or Syria develop nuclear weapons because of Dr. Khan's help. Mr. Bush portrays himself as Mr. Security, defending America from terrorism, but the paramount security threat we face is a nuclear 9/11, which could kill half a million Americans in one explosion. Whatever its electoral concerns, the White House simply can't be so complacent about tracking down Dr. Khan's other nuclear clients.

Aargh. My last column ended with a jet-lagged correction that repeated the error it was meant to fix. William Rood saw John Kerry's Silver Star incident, not the Bronze Star episode. Mea culpa squared.

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