South Korea and the United States were to wrap up their joint annual war game aimed at honing deterrence against North Korea on Friday, officials said, amid Pyongyang's strong criticism and threats of harsh retaliation.

Involving some 10,000 South Korean and 8,600 American troops, the computerized command post exercise, called Key Resolve, began on March 2 to improve the combined forces' operation and combat capabilities to deter threats from North Korea.

Seoul and Washington finished the first phase of the exercise on March 5, one day ahead of schedule, with the second phase to be closed later in the day after the after-action review, according to Seoul's defense ministry officials.

"The simulation exercise based upon various scenarios on the assumption of North Korea's infiltration into the South provided troops of the two nations with chances to have real-life experiences," a defense ministry official said on customary condition of anonymity.

"The joint plan on how to respond to North Korea's local provocations was also applied to the exercise," he added, pointing to the guideline that the allies draw on some 30 possible scenarios of the North's provocations in and around the region.

Another official said the two sides also implemented their customized deterrence plan against Pyongyang's nuclear threats and weapons of mass destruction.

Meanwhile, the joint field training drill Foal Eagle has been taking place as scheduled to run until April 24, according to officials.

The tactical training that mobilizes about 200,000 Korean and 3,700 American troops kicked off on March 2 and has involved a set of land, sea and air maneuvers.

Five countries -- Australia, Canada, Denmark, France and Britain -- have participated in the exercises, with the Neutral Supervisory Commission observing and monitoring them to ensure they do not break the Armistice Agreement signed at the end of the 1950-53 Korean War.

The large-scale annual exercises have further heightened tensions on the Korean Peninsula. On the first day of the exercises, North Korea fired two short-range missiles into the East Sea in an apparent saber-rattling.

Repeating its long-held claims that the exercises are "dress rehearsals" for a northward invasion with nuclear weapons, the North has issued near-daily threats of harsh retaliation against "hostile" forces.

But the allies have stressed the exercises have been staged on a regular basis and they are defensive in nature, aimed solely at bolstering readiness against a possible invasion by North Korea. (Yonhap)