By Ju-min Park and James Pearson SEOUL (Reuters) – North and South Korea appeared headed toward another clash, as Seoul refused an ultimatum that it halt anti-Pyongyang propaganda broadcasts by Saturday afternoon or face military action, and North Korea said its troops were on a war footing. South Korean Vice Defense Minister Baek Seung-joo said on Friday it was likely the North would fire at some of the 11 sites where the loudspeakers are set up on the South’s side of the Demilitarized Zone (DMZ) separating the countries. Tension escalated on Thursday when North Korea fired four shells into South Korea, according to Seoul, in apparent protest against the broadcasts.