SEOUL, 27th May, 2016 (WAM) — A South Korean naval vessel fired warning shots after a North Korean patrol boat and fishing boat crossed the countries’ disputed maritime border, Seoul’s defense ministry said.

The incident coincided with a prolonged push by North Korea for talks to reduce military tensions that escalated sharply after Pyongyang conducted its fourth nuclear test in January.

The two North Korean vessels crossed the Yellow Sea border around 7:30am (2230 GMT Thursday) but swiftly retreated after a South Korean navy patrol boat fired five warning shots, a ministry official said.