PAKISTANI SCIENTIST A.Q. KHAN was selling design information for building nuclear warheads to Libya for at least 18 months after U.S. and British intelligence knew about it, according to an article in today's Los Angeles Times. But Khan, the former head of Pakistan's atomic weapons program, had been running an international smuggling ring for nuclear technology for about 20 years before that, and although intelligence experts and government officials apparently had at least a generalized knowledge of Khan's illegal activities, the U.S. did nothing to shut his program down.

Some experts argue that the information we had was not strong enough to act on, or that the C.I.A. was too addicted to its own intelligence activities and wanted to keep spying instead of acting , or that a "watch and wait" approach helped the U.S. government make its case against Libya airtight.

"We could have stopped the Khan network, as we knew it, at any time," said Robert J. Einhorn, a top counter-proliferation official at the State Department from 1991 to August 2001. "The debate was, do you stop it now or do you watch it and understand it better so that you are in a stronger position to pull it up by the roots later? The case for waiting prevailed."

Current and former Bush administration officials say the patience paid off. They say that in late 2003, combined U.S. and British intelligence on Khan finally yielded enough information to persuade Libyan leader Moammar Kadafi to relinquish his nuclear technology and turn over conclusive evidence used to shut down the Pakistani scientist, who by then had been removed as head of his nation's primary nuclear laboratory.

But although the Bushies may argue that waiting gave them the leverage to convince Libya to renounce its nuclear ambitions and hand over the documentation that proved Khan was selling the nuclear technology, that one success came at a very high price. While the U.S. sat back and did nothing, Iran, North Korea, and possibly other countries got valuable information.

...for years Khan fed the nuclear ambitions of countries that the U.S. says have ties to terrorism and [that] pose major foreign policy problems.

"I don't see what was gained by waiting," said George Perkovich, a nonproliferation expert at the Carnegie Endowment for International Peace in Washington. "Iran got centrifuge equipment and knowledge at the very least, and possibly a weapons design. We don't even know what North Korea got."

Once again, we see that an ounce of prevention is worth a pound of cure.