US Secretary of Defence Lloyd Austin (L) shakes hands with Philippines' President Ferdinand Marcos Jr. during the 21st Shangri-La Dialogue summit in Singapore on May 31, 2024. Nhac Nguyen, AFP 

US Defense Secretary Lloyd Austin warned Saturday of China's coercive actions in the Indo-Pacific region while underscoring the need for dialogue to avoid conflict.

"The harassment that the Philippines has faced is dangerous, plain and simple," he said in a speech at the Asia Security Summit, also known as the Shangri-La Dialogue.

"We all share an interest in ensuring that the South China Sea remains free and open," he added, apparently referencing a series of aggressive Chinese moves against Philippine ships.

But he also stressed the importance of maintaining dialogue between militaries, saying, "There's no substitute for open lines of communication to avoid misunderstandings and miscalculations."

"The United States can be secure only if Asia is secure. That's why the United States has long maintained our presence in this region," he said.

Austin on Friday met with his Chinese counterpart Dong Jun on the sidelines of the gathering, expressing concern about China's "provocative" military activities near Taiwan. 

It was the first in-person talks between the two countries' defense chiefs since November 2022.

The United States has been enhancing security cooperation with its regional allies.

Austin said in the speech that such alliances and partnerships are the "greatest global strategic advantage" for the United States, pointing to joint development and production in their defense industries, including the project with Japan to develop a new missile capable of intercepting hypersonic weapons.

China criticized the US strategy articulated by Austin as "political rhetoric that sounds good but does no good," saying it builds "exclusive clubs with a Cold War mentality and a zero-sum mindset in the name of advancing regional cooperation."

Lt. Gen. Jing Jianfeng, deputy chief of staff of the Joint Staff Department of China's Central Military Commission, said the United States' true motive is to converge small alliances into a larger group, effectively creating an Asia-Pacific version of NATO and maintaining US hegemony.

Japanese Defense Minister Minoru Kihara said in his speech to the gathering later in the day that Tokyo will "fulfill a bigger responsibility" by working with like-minded countries to "deter unilateral changes of the status quo by force and create a desirable security environment" as well as aid countries under armed threat.

Kihara dismissed the view that boosting such alliances will heighten tensions in the region. 

He called for further cooperation to address mounting challenges, including North Korea's repeated ballistic missile launches in violation of U.N. Security Council resolutions.

"Japan will choose the rule of law, rather than force, solidarity rather than divisions and cooperation rather than coercion," the minister said.