KABUL (Reuters) - New U.S. Defense Secretary Leon Panetta arrived in Afghanistan on Saturday, saying he believed the strategic defeat of al Qaeda was within reach if the United States could kill or capture up to 20 remaining leaders of the core group and its affiliates. (http://feeds.feedburner.com/~ff/reuters/topNews?d=yIl2AUoC8zA) (http://feeds.feedburner.com/~ff/reuters/topNews?i=mPzY3t9f_6I:yEzcvE9GhMw:V_sGLiPBpWU) (http://feeds.feedburner.com/~ff/reuters/topNews?i=mPzY3t9f_6I:yEzcvE9GhMw:-BTjWOF_DHI) (http://feeds.feedburner.com/~r/reuters/topNews/~4/mPzY3t9f_6I)