The foreign ministers of Australia, India, Japan, and the United States are set to voice their opposition to the militarisation of the South China Sea during a meeting in Tokyo later this month, diplomatic sources in the Japanese capital disclosed on July 20.

This declaration comes amid escalating Chinese assertiveness in the region.

The ministers, part of the four-nation grouping known as the Quad, are also expected to agree on establishing a dialogue framework involving legal experts to uphold and strengthen the maritime rules-based order, the sources added.

According to a report by Japan's Kyodo News, Japanese Foreign Minister Yoko Kamikawa, as well as US Secretary of State Antony Blinken, Australian Foreign Minister Penny Wong, and Indian External Affairs Minister Subrahmanyam Jaishankar are anticipated to attend the gathering on July 29. This will be the first Quad foreign ministerial talks since September 2023.

A statement from last year's meeting urged the tackling of "challenges" in the South and East China seas. However, the upcoming meeting's communiqué is expected to adopt a sterner tone in light of a series of aggressive encounters between Chinese and Philippine vessels in the disputed South China Sea.

Preparations are reportedly being made to ensure the statement expresses the Quad members' continued opposition to the militarisation of the South China Sea in a clear and simple to understand manner. Coercive as well as threatening actions in the region will also be addressed, the same sources said.

The respective foreign ministers are further expected to express their nations’ concerns about territorial ambitions in the wider East and South China sea areas, while opposing any unilateral attempts by China to alter the current standing in the region, by force or coercion. At the same time the ministers will reaffirm their commitment to a "free and open Indo-Pacific," the sources noted.

Beijing has been militarising several outposts in the resource-rich South China Sea, where multiple countries including Malaysia, the Philippines, Taiwan, and Vietnam, have overlapping claims. The tiny state of Brunei also claims areas eyed by Beijing.

China's long-standing territorial claims against Taiwan in the region have also become increasingly aggressive, with naval and air patrols frequently violating Taiwanese waters and airspace.

Additionally, China has been making repeated incursions into territorial waters around Japan's Senkaku Islands, a group of islets in the East China Sea, which Beijing claims and calls Diaoyu.