UNITED NATIONS (AP) -- South Korea has handed over a letter officially referring North Korea to the U.N. Security Council over the ship sinking.
South Korea's U.N. Ambassador Park In-kook said he presented a letter to Mexico's U.N. Ambassador Claude Heller, the current Security Council president, on Friday.
He says the letter asks the council "to respond in a manner appropriate to the gravity of this situation."
It was the strongest step South Korea has ever taken toward making Pyongyang face international punishment.
Frosty relations between the Koreas have plunged since the sinking of a South Korean ship in March that killed 46 sailors.
An international investigation found it was torpedoed by a North Korean submarine.
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