SEOUL, July 25 (UPI) -- Anti-submarine tactics were on the agenda Sunday as a joint U.S.-South Korean military exercise got under way, a South Korean naval officer said.
The four-day exercises code-named "Invincible Spirit" were taking place off the eastern coast of South Korea despite North Korea's threat to use nuclear weapons if it is threatened.
Tensions on the peninsula remained high as the two Koreas trade allegations over the sinking of the South Korean warship Cheonan, which Seoul contends was attacked by a North Korean submarine in March.
"As an exercise to prevent attacks like the sinking of the Cheonan, we will drop sea mines and anti-submarine bombs during Tuesday's drill," the naval official, who declined to be identified, told the Yonhap news agency.
Yonhap said the exercises were taking in international waters well south of the north's territory.
The U.S. contingent is led by the aircraft carrier George Washington. In addition, the Air Force's cutting edge F-22 Raptor will be flying missions in Korean air space for the first time.