The United States and South Korea announced plans on Thursday for major annual joint military exercises as regional tensions run high following North Korea's third nuclear test.
A joint air, ground and naval field training exercise known as Foal Eagle will be held from March 1 to April 30. Separately, US and South Korean troops will stage a computer-simulated drill named Key Resolve from March 11-21.
Pyongyang habitually denounces the joint drills as a rehearsal for invasion.
Seoul and Washington insist the manoeuvres are defensive in nature. "The exercises are designed to enhance the security and readiness of (South Korea) and are deterrent in nature," they said in a statement.
Foal Eagle will include about 10,000 US forces along with a far bigger number of South Korean troops. Key Resolve involves about 3,500 US and 10,000 South Korean soldiers.
The United States has based troops in the South since the 1950-53 war and the force currently numbers 28,500.
South Korea has staged a series of military drills separately or jointly with the United States since the North launched a long-range rocket in December.
Earlier this month Seoul and Washington conducted a joint naval exercise with a US nuclear submarine off South Korea's east coast, followed by a joint air force drill.
Pyongyang insists the December launch put a satellite into orbit for peaceful research, but critics said it amounted to a banned ballistic missile test that marked a major advance for the communist state's nuclear weapons program.
Tension grew further on the Korean peninsula following the North's nuclear test on February 12.
North Korea said the test -- widely condemned by the international community -- was a direct response to UN sanctions imposed on Pyongyang after last year's rocket launch.
Pyongyang is already under international sanctions for conducting two nuclear tests in 2006 and 2009, which both came after long-range rocket launches.