North Korean leader Kim Jong Un has overseen military drills that included storming border guard posts, stepping up pressure on South Korea after saying he has the right to annihilate his neighbor and no longer seeks peaceful unification.

Kim called for his army "to usher in a new heyday of intensifying the war preparations in line with the requirements of the prevailing situation,” the official Korean Central News Agency reported Thursday. It also released photos of the drills showing troops and helicopters in training to take over a post similar to what South Korea has on its side of the border.

The training comes as the U.S. and South Korea this week kicked off Freedom Shield, one of their largest annual joint military exercises. A North Korean Defense Ministry spokesman said the two countries would "pay a dear price” for the drills that threaten the existence of the government in Pyongyang, KCNA said, raising the possibility of a military provocation as a display of anger.