The usually close, cooperative and happy relations between Singapore and Malaysia turned sour very quickly after the Tuas Incident in November 2018. A Malaysian maritime survey ship had anchored in Singapore's territorial waters in the Johore Straits, a kilometer wide channel that separates the two countries, and refused to leave despite warning from the Singapore coast guard and navy. This is perhaps the most serious and direct challenge by Malaysia to Singapore’s sovereignty since the Pedra Branca incident nearly a decade ago.

The incident is seen as a fallout of redrawing of port limits by Malaysia's Johore Port in the middle of 2018, which encroached into Singapore’s territorial waters. However, Malaysia claimed this was a response to Singapore’s decision to implement its Instrument Landing System (ILS) for airplanes landing at Seletar Airport, from the northern approach (Malaysia). The Singapore side claimed it has been consulting Malaysia since 2017 regarding the ILS, but the Malaysian side has always objected. The Malaysian Transport Minister later claimed, no less in national Parliament, that the Singaporean action damaged Malaysia’s national interest through the loss of airspace rights over Pasir Gudang, north of Seletar Airport. It also affected ship operations. There have been no plans for Malaysia to build high-rise buildings in Pasir Gudang. It is also not clear whether the ILS has been implemented, but the Singapore side claimed the ILS has in no way altered the flight path over Pasir Gudang that has been approved by Malaysia over many decades.

After Prime Minister Mahathir Mohammad retired in 2005, mutual trust and willingness to ‘give and take’ for the sake of deeper bilateral cooperation improved tremendously under successive Prime Ministers Abdullah Badawi and Najib Razak. There is a strong belief among Singaporeans that under these two prime ministers, the Seletar Airport situation would not have garnered such a Malaysian response.

Dr. Mahathir Mohammad has throughout his political career been known to be inimical to Singapore’s national objectives. Prime Minister Lee Hsien Loong of Singapore, sensing the need to be proactive, visited Kuala Lumpur a few days after Dr Mahathir came to power in May 2018 to give a good start to Malaysian-Singapore relations. That effort has apparently not moved Prime Minister Mahathir, and Singaporeans are now probably nostalgic about the better days of bilateral relations before May 2018.

More alarming, however, is the impact of the incident on the larger, though some would say lofty, ideals of international law, sanctity of inter-nation agreements, and particularly integrity of the ASEAN values of amity and cooperation. Both countries are founding members of ASEAN; although it is not designed to prevent bilateral disputes from happening, but ASEAN values, which both countries are expected to uphold highly, should have prevented this dispute from taking such a glitzy profile.

In an age when role of social media is extraordinarily large, the publicity over the incident and the readiness of both governments to use social media to put forward their case is noteworthy. While there is commitment among political leadership to always try to resolve disputes behind closed doors, this is not a rule, and domestic politics may trump ASEAN considerations. There is also a tendency for social media to strengthen nationalism and negate the fruits of quiet diplomacy.

In the Tuas Incident case, even as the maritime borders between Singapore and Malaysia in the Johore Straits have long been drawn and agreed to, expanding the port limits by one country into another country is simply disrespect and offensive. For the Singapore side, Malaysian displeasure over Pasir Gudang airspace is another reminder that it may need to slow down its development plans whenever the interests of its neighbours are affected. No doubt, the Singaporeans have not initiated the use of new airspace, but the use of the current airspace over Pasir Gudang is at the pleasure of Malaysia.

There is a list of other Singapore-Malaysia bilateral issues that are hot and are from the from the previous era when Mahathir was the Malaysian PM. These include the now suspended High-Speed Railway project (concluded under Najib's tenure), water supply from Malaysia to Singapore (30 year-old issue), and the future of the land link across the Johore Straits, which Mahathir would like to see (and Singapore objects to) broken up and replaced by a bridge. Although this is not an exhaustive list, PM Mahathir is likely to have taken the current course in the Johore Straits in order to pick up more bargaining chips in negotiations over other issues.

Singapore-Malaysia relations cannot be said to be the epitome of excellent neighbourly relations among ASEAN countries and the recent spate of their bilateral problems showcase power play and national interests, which everyone should recognise is the foundation of international order and international relations. It is the reassertion of such power that will be a setback for ASEAN’s pursuit of its values and ideals.

Dr David Koh is an analyst on Southeast Asia and international politics based in Singapore. He owns his own consulting business for politics and business that conducts analysis of Southeast Asia for clients from governments and businesses.