Australia on September 20 sought to reassure ASEAN that its new partnership with the US and UK, dubbed “Aukus”, is “not a defence alliance or pact”, as the bloc grows increasingly uncomfortable over the prospect of a more aggressive great power rivalry in its backyard.

ASEAN effectively acts as a buffer separating Australia and China and helps maintain peace and stability in the region, although some label Beijing’s swift rise as a superpower as a threat to the US and its allies.

At the same time, China’s increased militarisation in the South China Sea has long stirred tensions with several ASEAN member states that reject its sweeping claim over the globally important and busy sea trade route.

However, last week’s announcement that Canberra would be acquiring nuclear-powered submarines through its new Aukus trilateral partnership has spooked a number of countries, including in ASEAN, which collectively envisions Southeast Asia as a zone of peace, freedom and neutrality that is free of nuclear weapons.

Australian ambassador to ASEAN Will Nankervis has tried to ease the concerns, asserting in a statement on September 20 that Aukus was not a defence alliance.

Nankervis claimed that the security partnership, which will be formally signed in Washington this week, “did not change Australia’s commitment to ASEAN nor our ongoing support for the ASEAN-led regional architecture”.

“We are committed to continuing to foster a peaceful, secure region with ASEAN at its centre,” he said, while promising that Australia’s actions would be in line with ASEAN’s Nuclear Weapons Free Zone treaty.

Nankervis added: “Australia is also committed to upholding our obligations under the Treaty of Amity and Cooperation, as we have since we acceded in 2005, and to working with ASEAN and its member states to advance peace and prosperity in our region.”

In addition to ASEAN, the move has angered France, which has recalled its ambassador to Australia over its forfeiture of a previous submarine deal with it.

Australia currently enjoys good cooperation with ASEAN, and the country is expected to meet at the leadership level for the first time later this year. However, as experts have noted, the middle power country has been known to take ASEAN’s position for granted, and even tried to undermine or bypass ASEAN in its diplomatic initiatives.

Natalie Sambhi, defence analyst and executive director of Verve Research, said in a commentary for the Australian Strategic Policy Institute that “in this Western-led vision of the Indo-Pacific, Aukus unequivocally signals which relationships really matter for Australia.”

Another scholar, James Chin, professor of Asian studies at the University of Tasmania, said in an opinion piece that Aukus reinforced the widely held perception that Australia’s mantra of being part of the region was just “empty talk” and that it had “firmly signalled its intentions to put its Anglo allies in the US and UK first”.

“Aukus also reinforces the view that Australia cannot be accepted as a regional partner or player,” he said, as quoted in The Conversation.

In particular, Indonesia and Malaysia have come out strongly against Australia’s plan to arm itself with the help of the US and UK. Both noted that Aukus could increase power projections and provoke other powers to act more aggressively, including in the South China Sea.

Australian Prime Minister Scott Morrison was supposed to meet with President Joko “Jokowi” Widodo on his way back from Washington prior to the launch of Aukus, but reportedly declined due to conflicting schedules.

Even Singapore, a reliable ally for Australia in Southeast Asia, has expressed concern, albeit in a measured response.

In an official statement, Singaporean Prime Minister Lee Hsien-Loong expressed hope that the partnership would “contribute constructively to the peace and stability of the region and complement the regional architecture”.

Philippine defence secretary Delfin Lorenzana was quoted by Philippine Daily Inquirer as saying that, while the country recognised Australia’s right to improve its defence capacity, the Philippines intended to maintain good relations “with all countries in the region”. The country is one of a few in the region that has been in an alliance with the US.

Meanwhile, talks are under way for ASEAN to issue its own statement on Aukus. “It will be in the region’s interest if ASEAN could express its views on the recent development and uphold ASEAN centrality,” Indonesia’s senior diplomat for ASEAN affairs, Sidharto Suryodipuro, told the Jakarta Post on September 20.

The trilateral pact has been touted as part of a larger trend of contestation among superpowers China and the US that requires ASEAN to act in a decisive manner in the wider Indo-Pacific region.

Former Indonesian foreign minister Marty Natalegawa argued that the inception of Aukus, “like the revitalisation of the Quad before it”, was a reminder for ASEAN “of the cost of its dithering and indecision on the complex and fast-evolving geopolitical environment”.

The Quadrilateral Security Dialogue, or Quad, is another diplomatic grouping that involves the US, Australia, India and Japan, all of which have positioned themselves as a counterweight to China by promoting “a free and open Indo-Pacific” region.

After meeting virtually in March, leaders of the four countries are set to meet in Washington again this week.

“The forward looking and transformational initiatives of the past – precisely to anticipate and pre-empt recent developments – such as the Southeast Asia Nuclear Weapon Free Zone and the initiation of the East Asia Summit as a forum for dialogue on strategic issues among key countries of the Indo-Pacific, have needlessly been allowed to dissipate,” said Marty, who is also chairman of the Asia-Pacific Leadership Network for Nuclear Non-Proliferation and Disarmament (APLN).

“It is not too late for ASEAN to reassert its relevance. To proceed beyond expression of concern and hope. Instead, to rebuild mutual trust and reduce the possibility of costly miscalculation in the Indo-Pacific,” he added.