North Korea briefly activated radar for its surface-to-ship missiles Sunday, forcing South Korean naval vessels to move away from a disputed western sea border where the two countries' navies clashed last week, news reports said.
North Korea had warned it would take unspecified military action to defend itself following Tuesday's skirmish with South Korea. A senior South Korean military officer said the fighting left one North Korean crew member dead and three others wounded, while the South suffered no casualties.
Yonhap news agency reported that South Korea detected signs that North Korea activated its radar systems for anti-ship missiles at a western coastal site for about one hour starting at around 1 pm.
Yonhap, citing an unidentified military source, said South Korea ordered navy ships patrolling near the western sea border to move to safer areas.
The Defense Ministry said it could not confirm the report. A ministry official, speaking on condition of anonymity citing policy, said the radar is usually operated before North Korea test-fires a missile or engages in a drill. Yonhap didn't say why North Korea activated the radar. YTN television carried a similar report.
Tuesday's naval skirmish was the first in seven years between the rivals and came ahead of a trip to Seoul by President Barack Obama, who is scheduled to arrive Wednesday. Also, a special US envoy, Stephen Bosworth, is expected to visit North Korea by the end of the year to seek North Korea's return to international nuclear disarmament negotiations that it walked away from earlier this year.
The divided Koreas have long been at odds over their western sea border and fought battles in the area in 1999 and 2002. The North insists that a line imposed by the UN command at the end of the 1950-53 Korean War be redrawn farther south, a demand rejected by South Korea.