South Korea ? South Korea’s president said today his nation will no longer tolerate North Korea’s “brutality” and said the regime would pay for a surprise torpedo attack that killed 46 South Korean sailors.

President Lee Myung-bak vowed to take Pyongyang to the U.N. Security Council for punishment over the March 26 sinking of the warship. He also said Seoul would also cut all trade with the impoverished regime — part of measures primarily aimed at striking back at the isolated wartime foe diplomatically and financially.

In Beijing, U.S. Secretary of State Hillary Rodham Clinton said Pyongyang must be held accountable for the sinking of the Cheonan, and pushed to get China’s support of diplomatic action. China, a veto-wielding permanent seat holder on the Security Council and North Korea’s main ally and benefactor, has refrained from criticizing the neighboring nation.