Australian defence chief says China military buildup creating 'pressure' in Southeast Asia

Australia is referring to China’s rapid expansion of conventional military forces. Defence Minister Richard Marles called it the world’s biggest such buildup since the end of the Second World War. He said China had not explained why it was expanding so extensively. That uncertainty adds to regional concern.

The pressure is most visible in Southeast Asia, especially the South China Sea. China sends hundreds of coast guard, navy and other vessels to disputed areas. It also has militarised artificial islands there. The Philippines has reported that China’s military and coast guard presence in contested waters nearly doubled in September.

The buildup matters because Southeast Asian countries depend on existing rules and open regional security arrangements. Australia says China’s assertiveness challenges that order. Canberra is therefore strengthening defence cooperation with the United States, Japan, the Philippines and other regional partners.

The South China Sea is a major waterway in Southeast Asia. It includes maritime zones and islands claimed or controlled by several countries. The article describes parts of it as contested and critical to regional security. China claims almost the entire sea, making its boundaries and access politically sensitive.

The dispute exists because countries disagree over who has rights to particular waters, islands and maritime features. China sends coast guard, navy and other vessels into contested areas. It has also militarised artificial islands. These actions bring competing claims into direct contact and increase the risk of confrontation.

An international ruling found that China’s broad position had no legal basis. However, China continues operating in the disputed areas. That gap between the ruling and activity on the water has increased pressure on Southeast Asian states and encouraged Australia and the United States to deepen defence partnerships.

The article presents China’s military expansion as historically large. Marles calls it the biggest conventional military buildup the world has seen since the end of the Second World War. The article gives no exact total for China’s forces, so the scale cannot be measured precisely from the available figures.

Its maritime presence is substantial. Beijing deploys hundreds of coast guard, navy and other vessels to patrol disputed South China Sea areas. China has also militarised artificial islands. The Philippines reported that China’s military and coast guard presence in contested parts of the waterway nearly doubled in September.

Together, these figures show both broad military growth and concentrated activity at sea. The expansion is creating pressure for Southeast Asian countries and partners. Australia, Japan, the United States and the Philippines are responding with closer defence policy coordination and wider security cooperation.

If China keeps increasing military and coast guard activity in contested waters, pressure on Southeast Asian countries could intensify. More vessels and patrols would place competing forces in closer contact. That could make confrontations more frequent or harder to manage. The article does not predict a specific conflict, but it describes current activity as a regional challenge.

The Philippines provides a concrete example. It has faced years of confrontations with China in the South China Sea. Manila also reported that China’s military and coast guard presence in contested areas nearly doubled in September. A larger, more persistent presence can make disputed claims feel like an established reality.

The likely policy effect is closer cooperation among countries concerned about security. Australia, Japan, the United States and the Philippines have committed to stronger defence coordination. Australia also wants existing rules to continue applying, because it says those rules protect its influence as a middle power.

The international ruling rejected the legal basis of China’s position claiming almost the entire South China Sea. That decision addressed the legitimacy of China’s broad maritime claim. It did not end the disagreement or remove the contested areas. The sea remains a major security concern for Southeast Asian countries.

China continues to deploy hundreds of coast guard, navy and other vessels in disputed areas. It has also militarised artificial islands. The Philippines has reported years of confrontations with China and said China’s military and coast guard presence in contested waters nearly doubled in September. These actions continue despite the ruling.

That persistence matters because rules have force only when countries respect them in practice. Australia relies on a rules-based order and says rules give a middle power agency. Continued activity can therefore increase regional pressure and motivate stronger cooperation among Australia, the United States, Japan and the Philippines.

Australia, Japan, the United States and the Philippines are responding by coordinating defence policy through the informal “Squad.” Their cooperation reflects shared concern about China’s growing military presence and assertiveness. Australia says the four countries understand the pressures facing the region.

At their meeting, the Squad committed to greater defence policy coordination. Australia is also deepening defence cooperation with Southeast Asian countries, alongside Washington. The Philippines is a close Australian security partner and has experienced years of confrontations with China in the South China Sea. These partnerships connect countries facing related security pressures.

The broader approach is to strengthen collective security rather than respond alone. Marles urged countries to “double down” on friends and neighbours and work more closely together. The partnerships are intended to support the existing rules-based order, which Australia says gives middle powers influence and security.

A rules-based international order is a system in which countries rely on shared rules to guide behaviour, resolve disputes and support security. It is different from an arrangement based only on the strength of the largest military. The article connects this idea to maritime disputes and the continued application of international rules.

Australia’s Defence Minister says rules are especially important for a middle power. Australia may not match the largest powers in military scale, but shared standards can give it a recognised basis for action. Cooperation with partners can also reinforce those standards. The South China Sea ruling illustrates how international rules can assess competing claims.

Marles says China’s assertiveness challenges the existing order. Australia is therefore working more closely with Japan, the United States, the Philippines and Southeast Asian partners. Its aim is to preserve rules that provide agency, strengthen collective security and help smaller or middle-sized countries resist pressure.