The roar of massive Chinook helicopters filled the air near the inter-Korean border on Thursday as U.S.-ROK forces worked in tandem to build a temporary bridge over a river crossing, the finale to nearly two weeks of joint drills on defending the South against North Korean attack.

The “wet gap crossing” over the Imjin River, the site of one of the bloodiest battles of the 1950-53 Korean War, marked the end of the allies’ Freedom Shield springtime exercise that kicked off on March 10 and featured 16 field training drills.

While held annually, this year’s large-scale exercise took place under