One of the country's top weapons designers said he believes it is time for the United States to consider a radical shift in policy that would ultimately eliminate the nuclear arsenal. Joseph Martz, leader of a team designing a new generation of warheads at the Los Alamos National Laboratory, said in a series of interviews last week that he is troubled by how the debate on nuclear weapons policy in Washington is focused narrowly on the number of weapons needed for the future ... rather than on how to eradicate them entirely. Lab officials originally refused to give Martz permission to be interviewed for this article. Martz, however, said he decided to speak anyway in order to press ideas that he believes can reduce the risk of nuclear war and carve out a central role for the weapons labs, which have been threatened with budget cuts. Martz emphasized that he was expressing only his personal views and not those of the lab. But his comments still represent the first time in recent years that a senior scientist inside the weapons program has proposed making disarmament a concrete policy goal. Martz's aim is to help policymakers understand that, because of a more sophisticated grasp of weapons science, the United States can slowly dismantle its warheads and still protect itself. The country could also bolster its credibility as a leading voice for disarmament by ratifying the long-stalled treaty banning underground testing.