North Korea threatened in a statement on Monday to deliver surgical strikes on the South Korean loudspeakers in the demilitarized zone between the two countries, saying they create "psychological pressure." "We are demanding the immediate removal of this means of psychological pressure on the North... and [demand] the guilty be punished," Korean People's Army commander in the central sector of the demilitarized zone said in the statement, adding that if this was not done, the North would destroy the loudspeakers. In 2004, militants of both Korean states gave up using antagonizing propoganda tools in the Korean Demilitarized Zone, a buffer zone between the Koreas. However, South Korea resumed pressure on North Korean servicemen following the sinking of the South Korean Cheonan corvette on March 26. The 1,200-ton vessel sank near the disputed Northern Limit Line (NLL) in the Yellow Sea following a sudden explosion. Forty-six sailors died. A team of international investigators confirmed on Thursday suspicions that the ship was destroyed by a torpedo launched from a North Korean submarine. White House Press Secretary Robert Gibbs said on Monday the United States was ready to support a South Korean defense potential. He called for U.S. military officials to work tightly together with their South Korean counterparts in order to ward off any North Korean aggression. The conclusions of the investigation may lead to further deterioration of the already sour relations between the two Koreas and jeopardize international efforts to stop Pyongyang's controversial nuclear weapons and ballistic missile development programs. North Korea has already called the results of the investigation "a fabrication," and warned Seoul of stern response if the South retaliated with new sanctions against Pyongyang over the alleged attack on its warship. The two countries remain technically at war as their 1950-1953 conflict ended only in an armistice. Naval clashes between the two states over the disputed sea border took place in 1999, 2002 and last year. North Korea is one of the most militarized countries in the world. Its army comprises at least 1.2 million armed personnel. The state has a network of military facilities spread throughout the country, a developed weapons production line and a vast air defense system.