The 150 men and women, closely watched wherever they go, gave another stern performance at the official opening ceremony last night.
The crowd in the Incheon stadium gave the North Koreans one of the biggest cheers of the night but the delegation from the isolated state stared blankly ahead with barely a smile.
There was a similar stony silence for their welcome ceremony at the Incheon athletes' village on Thursday. The North Koreans looked on expressionless as a South Korean breakdance group leaped about to South Korean pop star Psy's hit "Gangnam Style".
A similar shield is thrown up whenever North Koreans, official or unofficial, come across the heavily militarised border for talks or other reasons.
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The South's strict National Security Law punishes unauthorised contact with North Koreans or activities deemed to be praising or sympathising with the communist state.
The North and South have remained technically in conflict since their 1950-53 war was ended by an armistice. A recent spike in tensions prompted speculation about what kind of reception the North's delegation would get in the South.
Hours before the opening ceremony, a South Korean navy ship fired warning shots to end a brief incursion by a North Korean patrol boat. The North also staged a series of missile and rocket launches in July and August.