ADEN (Reuters) - Yemeni forces backed by armed tribesmen launched an offensive to retake Zinjibar, capital of southern Abyan province, officials said on Sunday, after months of fighting with Islamist militants who seized the capital and another city. (http://feeds.feedburner.com/~ff/reuters/topNews?d=yIl2AUoC8zA) (http://feeds.feedburner.com/~ff/reuters/topNews?i=yikWzY9loMs:zH4GFabppgo:V_sGLiPBpWU) (http://feeds.feedburner.com/~ff/reuters/topNews?i=yikWzY9loMs:zH4GFabppgo:-BTjWOF_DHI) (http://feeds.feedburner.com/~r/reuters/topNews/~4/yikWzY9loMs)