South Korean warship

SEOUL, May 24 (UPI) -- South Korean officials halted most trade with North Korea and sought other sanctions against Pyongyang, which Seoul said sank one of its warships.

About two months after the South Korean corvette broke in two and sank due to an external explosion, Seoul said it was a North Korean torpedo that caused the damage and resulted in the deaths of 46 sailors.

North Korea denies a role in the incident but the lengthy investigation, which the North termed a "grave provocation," into the March 26 explosion suggested Pyongyang was behind the sinking.

"We have always tolerated North Korea's brutality, time and again," South Korean President Lee Myung-bak said. "But now things are different. North Korea will pay a price corresponding to its provocative acts. Trade and exchanges between South and North Korea will be suspended."

South Korea said it would continue some humanitarian aid to North Korea but took several other steps -- and asked for international support -- to sanction Pyongyang.

Those steps include tough warnings.

Lee, in a nationally televised address Monday, said: "From now on, the Republic of Korea will not tolerate any provocative act by the North and will maintain a principle of proactive deterrence. If our territorial waters, airspace or territory are militarily violated, we will immediately exercise our right of self-defense."

The United States expressed support for Seoul's moves but attention is now on China, long a supporter of North Korea, to see if Beijing will bring pressure on Pyongyang. Lee has a previously planned meeting with Chinese Premier Wen Jiabao on his schedule this week.