It's been 10-11 years since six South Koreans have been detained in North Korea, but there are still no words on whether they are still alive. Three of them are Christian missionaries and the rest North Korean defectors, who had resettled in the South. The missionaries, who had been involved in covert works to spread Christianity in the North, had all sentenced to hard labor for life after being convicted of plotting to overthrow the North Korean government. Experts say South Korea should intensify its campaign to elevate international awareness of the detainees so that North Korea could determine it can use them as a political bargaining chip in future negotiations.