pbr A 12-year-old boy in a school uniform has blown himself up at a Pakistani army recruitment centre, killing at least 31 cadets.br ppbr Officials say the youngster apparently walked into the compound unheeded.br ppbr The brazen bombing in the northwestern town of Mardan suggests militants are regrouping.br ppbr "It seems the Taliban are still a very potent force because they continue to attack installations, even if they have been quiet for a time," said former general Talat Masood.br ppbr In a sign of how nervous the government is about security, soldiers at the gates of the military compound searched drivers before allowing them to transport coffins inside.br ppbr Militant operations in recent months have been mostly sectarian and have not focused on military targets.br ppbr The Taliban have previously launched bold attacks on the military, nuclear-armed Pakistan's most powerful institution.br ppbr Last March, two suicide bombers killed at least 45 people in the city of Lahore, including nine soldiers.br ppbr In 2009, Pakistani Taliban militants disguised as soldiers attacked the army's headquarters in Rawalpindi and later took 42 people hostage in a nearby office building.