North Korean leader Kim Jong Un supervised a tank exercise and encouraged his armored forces to sharpen war preparations in the face of growing tensions with South Korea, the North’s state media said Monday.

Kim made those comments Sunday while visiting his top tank group, the Seoul Ryu Kyong Su Guards 105th Tank Division. The unit’s name marks how it was the first North Korean military unit to reach the South Korean capital in 1950 when a North Korean surprise attack triggered a war that dragged on for almost four years.

Tensions on the Korean Peninsula have heightened after Kim in past months dialed up his military demonstrations, including tests of nuclear-capable missiles designed to target South Korea, the United States and Japan, while issuing threats of nuclear conflict against its rivals.

Washington, Seoul and Tokyo have responded by strengthening their combined military exercises and updating their deterrence plans built around strategic U.S. assets.

Also Monday, North Korea said that Japanese Prime Minister Fumio Kishida offered to meet with Kim “as soon as possible,” but stressed that prospects for their countries first summit in about 20 years would depend on Tokyo tolerating its weapons program and ignoring its past abductions of Japanese nationals.

In a parliamentary session, Kishida said that a meeting with Kim is “crucial” to resolve the abduction issue, a major sticking point in bilateral ties, and that his government has been using various channels to hold the summit.

Kim’s sister and senior official, Kim Yo Jong, said in a statement that Kishida recently used an unspecified channel to convey his position that he wants to meet Kim Jong Un in person “as soon as possible.”

She said there will be no breakthrough in North Korea-Japan relations as long as Kishida’s government is engrossed in the abduction issue and interferes in the North’s “exercise of our sovereign right,” apparently referring to the North’s weapons testing activities.

Some experts say North Korea is seeking to improve ties with Japan as a way to weaken the trilateral Tokyo-Seoul-Washington security partnership, while Kishida also wants to use possible progress in the abduction issue to increase his declining approval rating at home.

North Korea and Japan don’t have diplomatic ties, and their relations have been overshadowed by North Korea’s nuclear program, the abduction issue and Japan’s 1910-45 colonization of the Korean Peninsula. Japan’s colonial wrongdoing is a source of on-again, off-again history wrangling between Tokyo and Seoul, as well.

There are concerns North Korea could further dial up pressure on its rivals and intensify its weapons testing activities in what is an election year in both the United States and South Korea. Kim Jong Un has supervised a series of missile tests and other military drills this year.

Photos published by North Korean state media on Monday showed Kim talking with military officers at an observation post and tanks with North Korean flags rolling through dirt, with at least one of the vehicles carrying a sign that read: “Annihilate U.S. invaders who are staunch enemies of the Korean people!”