The U.S. and South Korea kicked off large-scale joint military exercises on Monday to practice responses to North Korean nuclear and missile threats, a day after Pyongyang demonstrated its opposition to the drills by testing “strategic” cruise missiles.

The 11-day Freedom Shield exercises began at midnight and seek to strengthen the allies’ joint response capabilities against the backdrop of DPRK military escalations and a changing regional security environment, South Korea’s defense ministry confirmed to NK News.