Sen. Richard Lugar (R-Ind.) recently gave the Bush administration a passing grade on preventing nuclear terrorism [op-ed, Oct. 23]. Hard as it is to disagree with one of the most farsighted advocates for American security, I nonetheless found his case unpersuasive. Lugar accurately described what has been done, but he neglected to mention the more critical work left undone.

* Russia has thousands of nuclear weapons and weapons-grade materials that are vulnerable to theft. But in the two years after Sept. 11, fewer potential terrorist nuclear bombs in Russia were secured than in the two years prior.

* Weapons-grade material at research reactors in 20 developing countries remains at risk. At President Bush's pace, these reactors will remain vulnerable for another decade.

* With attention diverted to Iraq, Iran has advanced from years away to within months of completing the infrastructure for its nuclear weapons program. Bush has no strategy to prevent Iran from crossing the goal line.

* Although the president has declared a nuclear-armed North Korea "intolerable," he has tolerated North Korea's reprocessing of enough new plutonium for six nuclear bombs.

* Iraq had no nuclear weapons, as President Bush's hand-picked weapons inspectors have proven. The president and vice president chose to exaggerate intelligence on the threat by saying that Saddam Hussein had "reconstituted his nuclear program," thereby eroding America's credibility to face down real nuclear threats from North Korea and Iran.

In contrast, John Kerry's comprehensive strategy would combine moving urgently to lock down all nuclear weapons and materials at the source, directing negotiations to prevent the production of new nuclear weapons material, and aggressively pursuing would-be terrorists.

-- Graham Allison