“Mystify, mislead and surprise the enemy,” the ancient Chinese strategist Sun Tzu advised in The Art of War. Millennia later, China’s smaller neighbours are employing the same strategy against the Asian powerhouse to defend their interests. Following a long bout of delectable exchanges and a strategic charm offensive, leaders of major archipelagic nations in Southeast Asia have upped the ante, now directly challenging Beijing’s expansive claims in adjacent waters. In a major policy shift, Indonesia, the de facto leader of Southeast Asia, has openly rejected China’s claims within its traditional waters while bolstering its military presence in areas where claims overlap. It’s a dramatic departure from its long-standing whisper diplomacy under which it often has avoided direct diplomatic disputes with Beijing amid rising tensions in Asia’s maritime heartlands. We see a clear pattern of rising Indonesian assertiveness against China. Fed up with what they perceive as China’s revanchist designs, a growing number of neighbouring countries have risked disrupting fruitful economic relations with Beijing amid rising nationalism and anti-China sentiment at home. No less than President Joko Widodo, affectionately known as Jokowi, personally visited the Natuna Islands to affirm exclusive Indonesian sovereignty in the area. Asserting the country’s indisputable rights in the waters off the coast of the Natuna islands, which have witnessed a growing number of Chinese vessels in the past decade, Jokowi exclaimed: “We have a district here, a regent, and a governor here.” “There are no more debates. De facto, de jure, Natuna is Indonesia,” he argued in his visit to Natuna Besar island, leaving no room for compromise and negotiations with China. Not long ago, Jokowi was accused of being too close to China, a charge that dominated last year’s presidential elections in Indonesia. Rising anti-China sentiment in Indonesia, exacerbated by Beijing’s persecution of its Uygur Muslim minority in Xinjiang, has compelled Jakarta to take a tougher stand against China. Just weeks earlier, Malaysia provoked Beijing’s ire by submitting its extended continental shelf claim in the South China Sea to the United Nations, cutting right into China’s claims in the area. Only months earlier, Malaysian Prime Minister Mahathir bin Mohamad described his country as “a friend of China” with a long history of warm ties. Similar to Indonesia, the Muslim-majority country has also seen a rise in anti-China sentiment in recent years, first over Chinese infrastructure projects but later expanding to a whole range of issues, including the South China Sea and plight of Uygurs. Friends again? Chinese vessels in spat with Indonesia leave Natunas An influential Muslim Imam is now calling for a boycott of Chinese products, underscoring the hardening of popular sentiment against Beijing in neighbouring Muslim nations. Technically, Indonesia is a neutral non-claimant state in the South China Sea. But China’s ill-defined nine-dash line, which has no specific coordinates to date, effectively overlaps with waters off the Natuna islands, which are located about 1,100km (684 miles) south of the contested Spratly Islands. Jakarta has claimed that at least two Chinese coastguard vessels along with 63 fishing boats unilaterally entered Indonesia’s territorial waters off the Natuna islands in violation of its sovereignty. Under the United Nations Convention on the Law of the Sea (UNCLOS), a coastal state has full rights over the control of movement of foreign vessels within its 12 nautical miles of territorial sea. The only exception is the so-called right of innocent passage, which permits foreign armed vessels to move unimpeded in a straightforward manner without any hostile action or posturing. The UNCLOS also grants a coastal state exclusive sovereign rights over the exploitation of fisheries and energy resources within its 200 nautical mile exclusive economic zone. The only exception is two or more countries sharing legitimate overlapping claims and, accordingly, engaging in joint development agreements to explore and exploit resources in their shared areas. Indonesia deploys fighter jets to patrol Natuna islands at centre of China spat For Jakarta, Chinese fishing activities and the entry of armed Chinese coastguard vessels into its waters constitute a direct violation of its maritime sovereignty. In late December, Jakarta expressed a “strong protest” against Chinese incursions to the Chinese ambassador Xiao Qian. Jakarta accused China of a “violation of [its] sovereignty” and openly questioned China’s claims in the area, suggesting they had “no legal basis” and were “never recognised under UNCLOS”. Indonesia was further incensed when Chinese foreign ministry spokesman Geng Shuang insisted “whether the Indonesian side accepts it or not, nothing will change the objective fact that China has rights and interests over the relevant waters”. “The China Coast Guard were performing their duty by carrying out routine patrols to maintain maritime order and protect our people’s legitimate rights and interests in the relevant waters,” the Chinese official said. Indonesia responded in kind, maintaining, “China’s claims to the exclusive economic zone on the grounds that its fishermen have long been active there … have no legal basis and have never been recognised by the UNCLOS 1982.” Be vigilant, China’s embassy in Jakarta says as fishing row adds to tensions To China’s consternation, Indonesia invoked the 2016 tribunal ruling at The Hague, which was initiated by the Philippines and led to a legal rejection of China’s nine-dash line and historic claims in the South China Sea. Indonesia also bolstered its military presence in the area, signalling its willingness to put up armed resistance, if necessary. We see a clear pattern of rising Indonesian assertiveness. The signs range from adopting the aggressive “Sink the Vessels” policy, which targeted large numbers of illegal Chinese vessels, and pressuring China to clarify the precise legal basis and parameters of its claims. They also include calling for respect of international law after the 2016 arbitral tribunal ruling and a 2018 proposal for joint patrols by Asean states in the South China Sea to help de-escalate tensions. In 2017, Indonesia even renamed the contested area as the “North Natuna Sea” to assert its claims against the Chinese. Beyond the age-old tradition of diplomatic conviviality, major Southeast Asian nations are beginning to, evermore vocally, also resist China. Richard Heydarian is an Asia-based academic. Purchase the China AI Report 2020 brought to you by SCMP Research and enjoy a 20% discount (original price US$400). This 60-page all new intelligence report gives you first-hand insights and analysis into the latest industry developments and intelligence about China AI. Get exclusive access to our webinars for continuous learning, and interact with China AI executives in live Q&A. Offer valid until 31 March 2020.