New Defense Minister Minoru Kihara said Sunday that he is “very concerned” about China’s rapid military buildup and moves in the East and South China seas, calling trilateral security cooperation between Japan, South Korea and the United States “the cornerstone” of Tokyo’s response to an increasingly tense regional environment that also includes North Korea and Russia.

Kihara, who replaced his predecessor, Yasukazu Hamada, in a Cabinet reshuffle Wednesday, highlighted the need for continuity as Japan continues to shed some of the postwar constraints on its military amid a number of growing threats.

“In the face of the most severe and complicated security environment since the end of World War II, I would like to maintain the direction of my predecessor to fundamentally strengthen our defense capabilities,” he told an NHK television program.

On China, Kihara reiterated what has become an often-heard stance by members of Prime Minister Fumio Kishida’s administration: A pledge to “assert what needs to be asserted,” while calling for responsible behavior and continued engagement in dialogue on issues of concern and areas of potential cooperation.

“Both Japan and China have an important responsibility for the peace and prosperity of the region and the international community,” Kihara said. “We need to build a constructive and stable relationship.”

Bilateral ties have foundered over a spate of issues, including repeated incursions by Chinese government vessels into waters near the Japanese-controlled, Chinese-claimed Senkaku Islands in the East China Sea and Tokyo’s increasing outspokenness on the fate of democratic Taiwan, which Beijing considers a renegade province that must be unified with the mainland, by force if necessary.

But more recently, ties have hit a rocky stretch following Tokyo’s decision to release treated wastewater from the Fukushima nuclear power plant into the Pacific Ocean — a move that prompted a swift ban on all seafood imports from Japan. China says the science behind the discharge is incomplete, something Japan has disputed. Japanese officials say the Chinese move is intended to heap diplomatic pressure on Tokyo.

Asked about the recent summit between North Korean leader Kim Jong Un and Russian President Vladimir Putin and the two neighbors' reported push to seal a defense cooperation deal, Kihara said that while the results of Kim’s travels remain uncertain, Japan would “closely monitor any new developments.”

In response to the severe regional security environment, the defense minister said it was crucial for Japan to "strengthen ties with like-minded countries.”

“In this context, we would like to firmly consider the U.S.-Japan-South Korea relationship as the cornerstone of our efforts,” Kihara said.

Kihara, who served on the ruling Liberal Democratic Party’s ad hoc working group discussing a revision of Japan's regulations on the export of lethal weapons prior to taking up his Cabinet post, also voiced a need for continued, deeper discussion on amending those rules.

The defense chief said that the issue is “an important policy tool” and could be key in maintaining “a desirable safety and security environment for our country.”

“I would like to discuss this issue with the government and the ruling party based on the premise that the export of lethal weapons will not change the course of our country as a peaceful nation.”