TOKYO — Japan expressed interest Tuesday in participating in the NATO command for its Ukrainian mission based in Germany in what would be a major boost in ties with the largely European alliance.

Japanese Defense Minister Gen Nakatani announced his country’s interest during talks with NATO Secretary General Mark Rutte in Tokyo. After providing the war-torn country with defense equipment and support, Japan now wants to join NATO Security Assistance and Training for Ukraine, or NSATU, headquartered at a U.S. base in the German town of Wiesbaden.

Details of the mission, including the possibility of sending any Japan Self Defense Force members to Wiesbaden, were still to be discussed. But any Japanese cooperation was not expected to involve combat, in line with what has been Tokyo’s post-World War II tradition of limiting its military’s role.

Nakatani said Japan wants to further deepen security cooperation with NATO and that participation in the NSATU mission would help Tokyo learn lessons from Russia’s invasion of Ukraine.

“Both Japan and NATO face many challenges and our security environment has become increasingly more severe,” Nakatani said.

Japan has said that Russia’s war on Ukraine underscores that security risks in Europe and Asia are inseparable, and Tokyo has sought closer ties with NATO while also joining the United States in expanding defense ties with other friendly nations in the Indo-Pacific.

Rutte told Nakatani that China, North Korea and Russia are stepping up their military exercises and their cooperation, “undermining global security and that means what happens in Euro-Atlantic matters in the Indo-Pacific and vice versa.”

Japan considers China a threat in the region and has in recent years accelerated its military buildup, including preparing to acquire strike-back capability with long-range cruise missiles.

The NATO chief also raised concern about China’s arms buildup and military drills near Taiwan and called on the organization’s members and friendly nations to work together to keep free and open sea lanes in the region.

“China is supporting Russia’s efforts. China is building up its armed forces, including its navy, at a rapid pace,” Rutte told reporters earlier Tuesday after he briefly boarded Japan’s advanced multi-functional frigate Mogami docked in the Japanese naval port of Yokosuka. “We cannot be naive, and we really have to work together, assess what is happening.”

Rutte said NATO is worried about China’s military exercises near Taiwan and “we follow them very closely.”

Rutte told Nakatani that he hoped to deepen ties between NATO and Japan in a range of areas from crisis response operations to cyber defense, maritime security as well as defense industrial cooperation.

NATO has stepped up its ties with Japan, South Korea, Australia and New Zealand, known as the IP4, in recent years, with their officials attending NATO ministerial and summit meetings.

The United States wants NATO members to be more involved in the Indo-Pacific region, Rutte said. He welcomed U.S. Secretary of Defense Pete Hegseth’s recent trip to Japan to ensure Washington’s commitment to strengthen its alliance with Japan and presence in the region. He stressed its importance, noting that Japan is the only member of the Group of Seven that is not in NATO.

Rutte, visiting Japan for the first time since becoming head of the Belgium-based military alliance in October, will meet with Prime Minister Shigeru Ishiba on Wednesday.

Ishiba has advocated a NATO-like security framework in Asia, though he has not given details.

Countries with shared security concerns are strengthening ties as competition escalates between the United States and China. Beijing has criticized NATO’s growing ties with the Indo-Pacific partners, worried that Washington may move to form a NATO-like alliance in the region.