The U.S. and South Korean air forces will hold a biannual joint aerial exercise beginning Friday, as the allies’ large-scale drills continue to draw North Korea’s ire.

South Korea’s air force will lead the two-week Freedom Flag exercise with a focus on validating combined operational capabilities in preparation for the transfer of wartime operational control (OPCON), the service said in a news release Thursday.

Seoul’s Defense Ministry told NK News that the training will evaluate the ROK air force’s detection and interception capabilities, one of the key assessment tasks tied to the OPCON transfer.

South Korean President Lee Jae Myung