North Korea launched artillery exercises yesterday as top South Korean and United States military leaders held talks on the peninsula's security worries following the deadly North Korean artillery strike last month.
As the US chairman of the Joint Chiefs of Staff Admiral Mike Mullen and his South Korean counterpart General Han Min-koo met behind closed doors in Seoul, North Korea staged what appeared to be firing exercises near the disputed western sea border.
North Korean shells landed in the country's own waters north of South Korea's Baengnyeong island, a South Korean military official said.
North Korea also carried out an apparent military exercise within sight of the South's Yeonpyeong Island last month following the artillery assault on the island.
The prosecutor of the International Criminal Court said his office was starting a preliminary examination of possible war crimes by North Korea.
Luis Moreno Ocampo said that "no state requested our intervention" into the November 23 shelling of Yeonpyeong Island and the sinking of a South Korean warship in March and instead the requests came from South Korean citizens.
He said his office would assess whether a full-scale investigation of possible war crimes by North Korea should be carried out.
"We have a duty to assess if the court should intervene or not," Mr Moreno Ocampo said.
He said prosecutors must decide whether the incidents constituted war crimes, whether the court had jurisdiction, and whether the South Korean government was taking legal action.
The United Nations International Criminal Court, which began operating in 2002, is the world's first permanent war crimes tribunal. Under the treaty, the court can step in only when countries are unwilling or unable to dispense justice themselves for genocide, crimes against humanity or war crimes.
South Korea is one of 114 countries that ratified the treaty establishing the court, but North Korea does not recognise its authority.
Mr Moreno Ocampo said the goal of the preliminary examination was "just to collect information, to understand what's happened". He said his office would offer all parties an opportunity to send information about the incidents "if they want".
The shelling of Yeonpyeong Island killed two South Korean marines and two civilians. Forty-six South Koreans died in the sinking of the warship, the Cheonan.