Two South Koreans and 15 Russians have been held in North Korea for a week after their boat drifted into North Korean waters, Seoul officials said Wednesday. The crew members were aboard a Russia-flagged fishing boat when it was detained by North Korea on July 17, the Unification Ministry said in a statement. North Korea hasn’t responded to South Korea’s repeated calls for the repatriation of the two South Koreans, both men in their 50s and 60s, according to the ministry.