South Korea and the United States on Thursday wrapped up a major combined military exercise designed to reinforce deterrence against North Korean threats, the South's military said, as Pyongyang remained relatively mum over the exercise it has accused of being an invasion rehearsal. The annual computer-simulated Freedom Shield exercise drew to a close after kicking off March 4 amid heightened tensions over Pyongyang's recent saber-rattling, including artillery firings near the western sea border and a series of missile launches. This year's Freedom Shield took place with an aim to improve the allies' combined defense posture, focusing on multi-domain operations by utilizing land, sea, air, cyber and space assets, and countering the North's nuclear operations. On Wednesday, Defense Minister Shin Won-sik called on troops to master operational systems to "neutralize" the North's nuclear and missile networks as he visited a key wartime command bunker complex in Seongnam, just south of Seoul. The allies, howev er, did not train under a scenario of nuclear weapon use by North Korea, with that scenario expected to be incorporated in their major combined exercise in August. In connection with Freedom Shield, the two sides planned a total of 48 on-field exercises this month, more than double the figure in a similar period last year. Personnel from 12 member states of the United Nations Command, including Britain, also joined the exercise with the Neutral Nations Supervisory Commission, tasked with overseeing the armistice of the 1950-53 Korean War, observing them. The springtime exercise had raised concerns of Pyongyang conducting further provocative acts over the 11-day period, but the North did not stage high-profile military demonstrations, such as missile launches. Pyongyang has long denounced the allies' military drills as rehearsals for an invasion against it and has a track record of conducting missile launches in protest. Shortly after this year's Freedom Shield began, the North warned the allies would pay a "dear price" over the exercise, with its leader Kim Jong-un guiding a series of military field training over the exercise period, including one involving a newly unveiled tank Wednesday. The South's military said it also detected attempts believed to be made by the North to jam Global Position System signals around the northwestern border islands in the Yellow Sea from March 5-7. Source: Yonhap News Agency