North Korean leader Kim Jong Un joined his troops in training to operate newly developed battle tanks as he called for bigger efforts to prepare for war, state media reported Thursday.

The North’s tank training was seen as a response to the annual 11-day South Korean-U.S. military drills that are to end later Thursday. The North views its rivals’ exercises a rehearsal for invasion.

The North’s training on Wednesday was designed to inspect tankmen’s combat capabilities and involved the new-type main battle tank that Kim called “the world’s most powerful,” the official Korean Central News Agency.

During the training, heavy tanks moved around various simulated harsh combat circumstances and fired rounds at targets. Kim mounted one of the new-type tanks and drove it himself, “adding to the high militant spirit of the tankmen of our army,” KCNA said.

North Korea's Defense Ministry earlier vowed to carry out “responsible military activities” in reaction to the ongoing South Korea-U.S. military exercises in the South. Kim later supervised artillery firing drills.

The South Korean-U.S. training involve a computer-simulated command post training and 48 kinds of field exercises, twice the number conducted last year.

North Korea has dialed up its weapons testing activities since early 2022 in a bid to modernize and enlarge its nuclear and missile arsenals. The U.S. and South Korea have expanded their training exercises and a trilateral drill involving Japan in response.

Experts say Kim likely wants to use his upgraded weapons arsenal to win U.S. concessions like extensive relief of international sanctions on North Korea. They say North Korea is expected to extend its testing activities and ramp up warlike rhetoric this year as both the United States and South Korea hold major elections.