South Korea and the United States have again decided to put off their joint military drills in tense waters off the west coast of the Korean Peninsula, local media reported Tuesday, citing a defense ministry official. The two allies were originally scheduled to stage a four-day anti-submarine drills early this month, as part of the response to the Democratic People's Republic of Korea (DPRK)'s alleged sinking of a South Korean warship in late March that killed 46 sailors. But the naval drills were put off by two to three weeks due to lack of preparation. This time, the two countries are mulling to hold the exercise after the United Nations Security Council (UNSC) takes measures against the DPRK, because the two sides must 'take into account the diplomatic situation,' Seoul's Yonhap News Agency quoted an unnamed defense ministry official as saying. The drills will reportedly be participated by some 20 warships, including the U.S. George Washington, a nuclear-powered 97,000-ton carrier, Aegis destroyer and a nuclear-powered submarine belonging to the U.S. 7th Fleet. The South Korean Navy will also mobilize a 4,500-ton destroyer, a submarine and F-15K fighter jets. Seoul formally referred the case of warship sinking to the UNSC early this month after it concluded that the 1,200-ton navy frigate Cheonan was torpedoed by the DPRK. But the DPRK denied any involvement and asked the UNSC to act to help find the truth of the incident. 