South Korea planned to repatriate the other 27 North Koreans and their boat to the North on Friday, the Red Cross said in a statement. The Red Cross conveyed those plans to its counterpart in the North but got no immediate response, South Korean Red Cross officials sai

Four of the 31 North Koreans held after their boat strayed into South Korean waters have asked to stay in the South, officials said on Thursday, a move likely to draw an angry response from Pyongyang.

South Korea planned to repatriate the other 27 North Koreans and their boat to the North on Friday, the Red Cross said in a statement. The Red Cross conveyed those plans to its counterpart in the North but got no immediate response, South Korean Red Cross officials said.

The 31 North Koreans were aboard a small fishing motorboat that drifted across the Koreas’ western sea border about one month ago.

More than 20,000 North Koreans have fled to South Korea, most via China, since the end of the Korean War in 1953, with defections surging in recent years amid economical hardship in the North. The South Korean policy is to accept those who choose to defect and to repatriate those who wish to return home.

North Korea, which has called for the entire group’s repatriation, is expected to criticize South Korea over its decision to accept the four defectors, said Kim Yong—hyun, a North Korea analyst at Seoul’s Dongguk University.

The North’s criticism isn’t expected to seriously hurt ties between the two Koreas, however, because it’s not the first time for South Korea to accept North Korean asylum—seekers, Mr. Kim said.

North Korea has been enraged since Monday’s start of annual South Korea—U.S. drills. Pyongyang calls them a rehearsal for invasion.

The Koreas’ relations plunged to one of their lowest levels in decades last year over the sinking of a South Korean warship blamed on Pyongyang and North Korea’s shelling of a front—line South Korean island. A total of 50 South Koreans were killed.

The Korean peninsula officially remains in state of war because the Korean War ended with an armistice, not a peace treaty.

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