TOKYO (AP) — United States (US) Secretary of Defence Lloyd Austin stressed the importance of communication during a stopover Thursday in Tokyo, calling it unfortunate that his Chinese counterpart is refusing to meet him at an upcoming annual security conference in Singapore, which both men are attending.

On the way to the annual Shangri-La Dialogue Asian security summit this weekend, Austin held talks with Japanese Defense Minister Yasukazu Hamada. Noting China’s increasingly assertive military actions in international airspace and waterways in the region, he told a joint news conference in Tokyo, “The provocative intercepts of our aircraft and also our allies’ aircraft, that’s very concerning, and we would hope that they would alter their action.”

The United States military said Tuesday that a Chinese fighter jet flew aggressively close to a US reconnaissance aircraft over the South China Sea, forcing the American pilot to fly through the turbulent wake.

“I’m concerned about at some point having an incident that could very, very quickly spiral out of control,” Austin said. “I would welcome any opportunity to engage with leadership. I think defence departments should be talking to each other on a routine basis or should have open channels for communication.”

Although Beijing said there will be no meeting between Austin and his Chinese counterpart at the security summit, Hamada is expected to attend and meet with Chinese Minister of National Defense Li Shangfu on the sidelines.

Japan and China set up a defence hotline in March to improve communication and avoid accidental encounters in the tense region, and Hamada and Li recently held their first telephone talks on the hotline.

Washington and Beijing have yet to hold such a talk, and when Austin phoned their crisis line in February, the call went unanswered.

“We need to strengthen our cooperation of Japan-US, and Japan-US-South Korea,” Hamada said Thursday. The two criticised North Korea’s failed rocket launch Wednesday for using ballistic missile technology that’s prohibited under United Nations’ Security Council resolutions, and affirmed further cooperation between them and with South Korea in case of another launch attempt.

Ties between Japan and South Korea have improved rapidly in recent months under Washington’s pressure in the face of growing regional threats from China, North Korea and Russia. Tokyo and Seoul are also discussing real-time sharing of North Korea’s missile launch data.

Austin said the United States stands with Japan and South Korea in the face of Pyongyang’s provocations and that “the United States will take all necessary measures to secure to ensure the security of our homeland in the defence of our allies.”

Austin and Hamada agreed to strengthen extended deterrence for Japan, which includes US nuclear weapons.

“I am here to reaffirm America’s unwavering commitment to Japan. This includes extended deterrence and provided by the full range of U.S. conventional and nuclear capabilities,” Austin said.

The two ministers also agreed to step up and expand their defence industries and strengthen multinational formats, including with South Korea, Australia, the Philippines and India to reinforce their Indo-Pacific security cooperation.

At a meeting later Thursday with Austin, Japanese Prime Minister Fumio Kishida said Japan wants to further strengthen its deterrence and response capabilities by working with the United States, especially focusing on Japan’s use of strike capability.

Under its new security strategy issued in December, Japan pledged a military buildup that includes strike capabilities and doubling defence spending — a break from its postwar self-defence-only principle.