pyeongchang south korea set host winter olympics february south korea conduct series security drill tuesday prepare terror attack range hostage situation vehicle ram stadium bomb-attached drone police firemen among around 420 personnel participate exercise hold front olympic stadium pyeongchang 80 km 50 miles heavily fortify border north korea simulate drill members swat team shoot drone bomb attach fly toward bus carry athletes another part mock exercise terrorist take hostage athletes bus try ram vehicle stadium gun police officer gas mask also remove chemical bomb anxiety korean peninsula rise recent months due series missile test north korea continue pursuit nuclear weapons defiance u.n. sanction warn unite state please keep mind accidents always happen one expect south korean prime minister lee nak-yon say please check last minute whether security loopholes lee mention north korea south korea defense ministry friday flag risk north korea could resort terrorist cyber attack spoil international events 5,000 arm force personnel deploy winter game accord south korean government officials document review reuters pyeongchang organize committee 2018 game pocog also hire private cyber security company guard hack attack north tender document show minimize risk provoke aggressive north korean reaction game south korea ask washington delay regular joint military exercise olympics financial time report spokesman south korea defense ministry say tuesday nothing decide south korea conduct anti-terror drill ahead winter game