In 1950, the United Nations actually stepped up to the plate (with the Soviets conveniently absent so they could not use their Security Council veto) in 1950 to halt North Korean aggression against South Korea.
That effort was successful, but incomplete, since the war was merely interrupted with a ceasefire and not a peace treaty. The UN still stands, in theory, against North Korea.
So the latest North Korean killing spreee against South Korea seems tailor made for the UN's stated reason to exist. But North Korea is warning the body against even talking about the attack:
South Korea last week officially asked the U.N. Security Council to punish North Korea, after an international investigation said a North torpedo attack sunk a South ship in March, killing 46 sailors. North Korea flatly denies responsibility and says any punishment would trigger war.
Sin Son Ho — North Korea's permanent representative at the U.N. — sent Security Council president Claude Heller a letter Tuesday saying the council must not open a debate on the "the unilaterally forged" investigation results because that would fringe upon the North's sovereignty, the official Korean Central News Agency said in a dispatch from Pyongyang.
"No one would dare imagine how serious its consequences would be" over security on the Korean peninsula if the debate starts, Sin said in the letter, according to the KCNA dispatch.
So will it be collective defense? Or collective looking away? If the UN can't face down this threat, why bother with it?