In another sign that the line between the cyberworld and the worldworld is getting blurrier, the US military is talking tough about online attacks. The Pentagon is beginning to make public its strategy in dealing with attacks that could severely disrupt infrastructure such as power plants and major transportation systems. “If you shut down our power grid, maybe we will put a missile down one of your smokestacks,” said a military official. This position raises a bunch of new issues, of course, including how well the military can determine precisely where an attack originated and what level of hacking would be cause for military retaliation.