<p>ISLAMABAD, Pakistan — Amid stepped up attacks in Afghanistan, the Taliban's elusive leader Mullah Mohammed Omar has issued a fresh call for a holy war against U.S. troops and Afghans who work with them.</p>
<p>His latest decree, released in posters widely displayed in eastern Afghanistan, carries the signatures of 600 Islamic clerics reminding the faithful of their duty to wage jihad, or holy war.</p>