The Fifth ASEAN Defence Ministers' Meeting-Plus (ADMM-Plus), now an annual event, was held in Singapore on 20 October 2018. The Meeting was chaired by Dr. Ng Eng Hen, Minister for Defence, Singapore. For the first time since inauguration, all 18 Defence Ministers from the ten ASEAN Member States and eight ASEAN Dialogue Partners, namely Australia, the People's Republic of China, the Republic of India, Japan, New Zealand, the Republic of Korea, the Russian Federation, and the United States of America attended the Meeting. The Deputy Secretary-General of ASEAN was also present.

The Defence Ministers affirmed the ADMM-Plus as the de facto multilateral security mechanism in the Asia-Pacific. In addition to the Meeting proper where common security challenges were discussed, the Experts' Working Groups for the seven domains of maritime security, humanitarian assistance and disaster relief, counter-terrorism, military medicine, peacekeeping operations, humanitarian mine action, and cyber security also provided for military-to-military interactions and cooperation. All Defence Ministers further affirmed ASEAN's centrality in the regional security architecture.

During the Meeting, specific initiatives to deal with terrorism and prevention of mishaps in the air for military aircraft were agreed upon. Consensus was achieved among all countries that resulted in the issuance of two Joint Statements by the 5th ADMM-Plus.

The Joint Statement on Preventing and Countering the Threat of Terrorism reaffirmed ADMM-Plus' collective commitment to strengthen regional cooperation against this common security threat. In particular, a common information-sharing platform was proposed and supported. The Defence Ministers also agreed to step up practical military-to-military cooperation through the ADMM-Plus Experts' Working Group on Counter-Terrorism (EWG on CT).

The second Joint Statement on Practical Confidence Building Measures highlighted the importance of ensuring the safety and security of the sea and air lanes which were essential for global commerce. In acknowledging the risks, the Defence Ministers agreed to promote communication, mutual trust and confidence and reduce miscalculations and mishaps in the region. During the Meeting, Singapore proposed a set of guidelines on air military encounters to promote a safe operating environment. The proposal received unanimous support in-principle; various countries also lent support to the attendant documents on operational procedures. This represented the first such agreement in a multilateral defence establishment. This set of air guidelines, together with previous ADMM-adopted initiatives such as the ASEAN Direct Communications Infrastructure, the ADMM Guidelines for Maritime Interaction, as well as the ADMM-Plus EWG exercises and ADMM-Plus' agreement to subscribe to the Code for Unplanned Encounters at Sea (CUES), were significant measures to enhance regional peace and stability.

The Defence Ministers also exchanged views on other common security challenges, including the situation in the Korean Peninsula, recent developments in the South China Sea, the proliferation of weapons of mass destruction, and cyber threats. They emphasised the need to enhance mutual trust and confidence, exercise self-restraint in the conduct of activities, avoid actions that may further complicate the situation, and pursue peaceful resolution of disputes in accordance with international law, including the 1982 UN Convention on the Law of the Sea (UNCLOS). In this regard, the Defence Ministers expressed the hope for the good progress and expeditious conclusion of the Code of Conduct in the South China Sea.

The ADMM-Plus further noted that the ASEAN Defence Ministers had agreed on the selection criteria for observers during the 12th ADMM held on 19 October 2018. This initiative provided non-Plus countries with opportunities to contribute expertise and capabilities to the region through the EWGs.

The Defence Ministers also witnessed the ADMM Chairmanship Handover Ceremony from Singapore to Thailand, and expressed full support for the upcoming 13th ADMM and 6th ADMM-Plus in Thailand in 2019.