SEOUL - North Korea has declared a no-sail zone for its ships off its east coast, South Korean media reported on Monday, suggesting more missile launches are possible before the US defense chief visits Seoul this week.
Pyongyang fired four short-range missiles off its west coast on Friday in what South Korea called a bid to stoke tension during its annual joint military drills with the United States.
The two Koreas are locked in a tense standoff, trading harsh rhetoric recently over the arrest by Pyongyang of two South Korean nationals it accused of espionage.
It was not clear if the latest warning for ships to stay clear of an area off the Korean peninsula's east coast was a direct indication of an imminent missile launch.
"There are no signs of peculiar movements," South Korean defence ministry deputy spokesman Na Seung-yong told a briefing. Na said a no-sail warning had not been sent to Seoul or the International Maritime Organisation (IMO).
North Korea has reported to the IMO before previous long-range missile launches, which it has claimed were rockets to launch satellites. The North is under UN sanctions banning it from developing ballistic missile technologies.
US Defense Secretary Ashton Carter is due to start a three-day visit to South Korea on Thursday.