By Hamid Shalizi KABUL (Reuters) - A Taliban suicide bomber and six gunmen attacked the Afghan parliament on Monday as lawmakers met to consider a new defense minister, and another district in the volatile north fell to the militants as they intensified a summer offensive. The brazen assault on the symbolic center of power, along with territorial gains elsewhere, highlight how NATO-trained Afghan security forces are struggling to cope with worsening militant violence. Fighting has spiraled since the departure of most foreign forces from Afghanistan at the end of last year.