Just a few months ago, the supreme leader of North Korea, Kim Jong Il, appeared to be a lame duck in both senses of the term. In public appearances, he looked deathly ill after suffering a severe stroke in 2008, and preparations were reportedly underway for one of his sons to succeed him.

Fast-forward to today, and Kim is lame no more. Not only has he regained his vigor, judging by his performance during recent visits by Bill Clinton and Chinese Premier Wen Jiabao, but talk of his succession has also become muted. Kim is unquestionably still the man to do business with in Pyongyang.

But what kind of deals can be made? The United States, along with China, Russia, South Korea and Japan, would like the North to return to the six-party negotiations and, moreover, live up to its earlier nuclear disarmament pledges. The first part, probably preceded by bilateral talks between North Korea and the U.S., probably will take place soon. But the ultimate goal appears even more remote, if it were ever realistic.

North Korea has made it abundantly clear that it will not give up its nuclear weapons — "unthinkable ... even in a dream" as one of its officials recently put it. Possessing a nuclear deterrent is part and parcel of the North's declared intention to become a "strong and prosperous state" by 2012 — the 100th anniversary of the birth of its founder, Kim Il Sung, and the 70th birthday of his son, the current leader.

For Kim Jong Il to relinquish his nuclear arsenal ahead of 2012 — the most potent element of North Korean power that was more than likely promised to his generals to secure their continued fealty to him and his appointed successor — is indeed unthinkable.

And 2012 also marks the year when South Korea takes control of all United Nations ground forces — including U.S. ground troops — during wartime on the peninsula. That the North knows Seoul enjoys conventional superiority over its rapidly atrophying army only reinforces the need for a nuclear deterrent.

China alone has the leverage to force North Korea to give up its nukes by withholding vital food and energy supplies. But no one seriously believes China would use its leverage because that would risk destabilizing its neighbor, to say nothing of opening up the possibility of unification with the South — a military ally of the U.S. — if the North were to subsequently collapse.

Why bother talking to Pyongyang if it's going to be fruitless? Three reasons still make it worthwhile:

First, for as long as there are six-party talks focused on denuclearization, North Korea will be denied what it craves most: formal recognition as a nuclear power. And the other players — the U.S., China, Japan, South Korea and Russia, and by extension the larger international community — can claim they have not capitulated to the North Korean "fait accompli." Otherwise, Iran and other nuclear aspirants would be emboldened.

Second, if carefully negotiated, the talks could also put a cap on further nuclear weapons development by North Korea. A moratorium on further testing would be a good start. The other five parties could also collectively make clear to North Korea the prohibitive consequences should it ever transfer nuclear materials to nonstate actors.

Third, the talks and the potential inspections of nuclear sites that could conceivably follow could provide a window on what is happening inside North Korea. Moreover, they provide a useful and ready diplomatic mechanism to manage the consequences of severe instability in North Korea should the situation suddenly deteriorate.

After all, even North Korean ducks don't live forever.