This standpoint also reaffirms that in managing its great power relations, Indonesia maintains an “equidistant” approach. In its quest for regional stability, Indonesia has worked hard to avoid being dragged into geopolitical tensions or being forced into partisan positions. It is not in Indonesia’s interest to be in the middle of competition between great powers.

Such acquisition of nuclear submarines raises concerns that an arms race characterized by increasing power projection capabilities in the region may be imminent. This new strategic posture is clearly intended to bolster up deterrence in contested areas in the Indo-Pacific. These kinds of endeavors to build up powerful military prowess are likely to trigger and attract further counterreactions.

In response to this challenge, other powers in the region may decide to compete and intensify their own military buildup. As a result, direct conflict among the great powers of the region becomes more probable.

Considering this, Indonesia has called on Australia to maintain its commitments toward regional peace, stability and security in accordance with the Treaty of Amity and Cooperation (TAC), to which Australia acceded in 2005. As a code of conduct governing interstate relations in the region, the TAC requires Australia to cooperate with countries, both within and outside Southeast Asia, in the furtherance of world peace, stability and harmony. In line with the spirit of Southeast Asia as the Zone of Peace, Freedom and Neutrality, any action that may escalate tension and may lead to arms competition in the region needs to be avoided.

Australia and other parties concerned in the Indo-Pacific need to engage in dialogue in order to peacefully settle any differences among them. Under the TAC, the state parties “shall have the determination and good faith to prevent disputes from arising”. In cases of disputes likely to disturb regional peace and harmony, they are also obliged to refrain from the threat or use of force.

Regional peace and harmony may only be maintained if Australia and any other parties concerned also continue to uphold international law, in particular, the 1982 United Nations Convention on the Law of the Sea (UNCLOS). In spite of the political dynamics of the strategic competition, it remains imperative that the rule of law at the international level is respected. It will make the effort to manage the tension in the region more predictable and legitimate.

As far as the issue of non-proliferation is concerned, the acquisition of such submarines may be examined from at least two aspects. Besides the issue of compliance with the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), some have also questioned the consistency of Australia’s actions with the Treaty on the Southeast Asia Nuclear-Weapon-Free Zone (SEANWFZ Treaty).

In regard to the first issue, while announcing its plan to acquire nuclear submarines, Australia reaffirmed its undertaking not to acquire nuclear weapons. It will remain a non-nuclear weapons state and will continue to meet its obligations under the NPT and other relevant agreements, including with the International Atomic Energy Agency (IAEA) regime.

It is important to note that the NPT only prohibits states that did not possess nuclear weapons before Jan. 1, 1967, from acquiring them in the future. The treaty is silent about the use of nuclear energy for other military purposes. The reality is that the use of nuclear energy for non-peaceful objectives is outside the scope of the NPT.

The acquisition of highly sensitive nuclear submarine technology by Australia, a non-nuclear weapons state under the NPT, may also raise concerns regarding the risk of proliferation of fissile materials. As nuclear submarines are powered by an “onboard nuclear reactor,” these reactors require uranium that has been highly enriched to a certain degree to work.

The problem is that the IAEA cannot effectively safeguard naval reactors such as those in submarines that are by their very nature, location and manner of use essentially inaccessible. For that reason, the IAEA provides a mechanism to accommodate the use of nuclear material in a non-prescribed military nuclear activity, such as for nuclear propulsion in naval submarines. States may request that the use of nuclear material in this manner be excluded from IAEA safeguards. This may possibly increase the risk of the undetected diversion of the use of nuclear material from its stated use to power nuclear submarines.

To be clear, Australia will undertake this activity in a way that reflects responsible nuclear stewardship, given Australia’s exemplary nuclear-proliferation credentials. However, because Australia will be the first country without nuclear weapons to develop such capabilities, the acquisition of nuclear submarine technology may set a dangerous precedent. In the future, other countries may be inclined to follow that same path. If this were to occur, it may lead to the alarming possibility that those countries may gain access to an abundance of new nuclear material.

On the second issue of the consistency of Australia’s actions with the SEANWFZ Treaty, it is clear that Australia’s decision does not constitute a breach of the SEANWFZ Treaty as Australia is not a state party to it. Furthermore, the treaty provides that each ASEAN country may decide for itself whether to allow the visit of foreign ships to its ports or navigation by foreign ships through its territorial sea in a manner not governed by the rights of the innocent passage, archipelagic sea lane passage or transit passage. Ultimately, it is up to each ASEAN country to decide whether or not to allow nuclear submarines to pass.

We can conclude, therefore, that while Australia’s recent actions are alarming, no international legal norm appears to be violated for the time being. Nonetheless, there are legitimate reasons for Indonesia to be cautious of this recent development because Australia may change the geopolitical landscape of the region. There is no such thing as the acquisition of nuclear-powered submarines without the possibility of sparking a nuclear arms race.

Australia as the ASEAN’s very first dialogue partner must ensure that the implementation of AUKUS will not contribute to any act that may defeat the purposes of the SEANWFZ. AUKUS needs not affect Australia’s support of the ASEAN-led regional architecture. In this regard, Indonesia welcomes the continuing commitment of Australia to fostering a peaceful, secure region with ASEAN at its center.

Deeper conversations on the partnership are essential to building mutual trust, confidence and transparency. To be effective, this endeavor should be carried out at all levels of diplomacy.

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The writer is a senior Indonesian diplomat. The views expressed are his own.