Dressed in military camouflage with an assault rifle at the ready, "Prof" Yeh peers from behind a vehicle in a parking lot outside Taipei, scanning his surroundings and waiting for a signal to advance. Yeh actually works in marketing, and his weapon is a replica -- but he is spending the weekend attending an urban warfare workshop, to prepare for what he sees as the very real threat of a Chinese invasion. He is not alone -- the organisers of the urban combat course say their students have nearly quadrupled since February. Firearms and first aid courses have also seen increased enrolment. IMAGES AND SOUNDBITES ARRANGED IN SEQUENCES