seoul traffic halt movie screen interrupt hundreds thousands people across south korea direct underground shelter wednesday part civil defense drill practice case attack north korea south koreans familiar preparations see many decades since height cold war tension neighbor still technically war many people become inure danger time government try inject urgency get people take part amid surge tension north korea weapons program exchange dire warn nuclear war swear enemy unite state need practice still war north korea people insensitive threats say hwang jae-min 30-year-old prison guard happen watch movie seoul cinema complex siren herald begin drill hwang one 50 moviegoers lead underground take shelter imaginary north korean air raid siren sound around country government officials police flag traffic try shepherd pedestrians near shelter skeptics doubt orchestrate exercise would much use come real war strongly believe need drill seem work properly say choi in-sook 45-year-old housewife stroll city street siren go run cover need perform like real war say drill part annual joint military exercise conduct south korean u.s. force begin monday run aug. 31 north korea denounce reckless step toward nuclear war north korea routinely denounce military exercise u.s. south korean force regard thinly disguise preparations invade south korea state run television broadcast scenes 20-minute drill live first time two years hope drum enthusiasm jung han-yol director ministry public affairs safety civil defense division concede fact participation voluntary mean drill might lack credibility cho won-cheol emeritus professor civil environmental engineer yonsei university seoul say always problem get people involve government preparations war people believe happen reason drill work well country civil defense drill always practice mostly government civil officials civilians cho say south korea main ally unite state technically still war north 1950-53 conflict end truce peace treaty south koreans practice case north korea attack little urgency