The question is suddenly urgent: Could the inconceivable happen? President Bush has previously warned the world that Osama bin Laden is seeking to develop weapons of mass destruction. Now, bin Laden himself claims to have chemical and nuclear weapons -- and "the right to use them." We cannot know for certain whether he is bluffing, but Homeland Security Director Tom Ridge has confirmed that documents detailing how to make nuclear weapons have been found in an al Qaeda safe house in Kabul. And we can certainly expect that as the noose tightens aroundthe terrorist''s neck, he and his associates will become increasingly desperate.