Crack warships from the PLA's three naval fleets jointly exercised in the disputed South China Sea in a move that was hailed by the state media as unprecedented. The drills by the People's Liberation Army Navy in strategic waters on Monday come at a sensitive time; the United States and South Korea are conducting their own joint military drills off the Korean Peninsula. The US further angered Beijing last week by declaring that the resolution of disputes in the South China Sea is in the US' 'national interest'. The Ministry of Defence and state media did not mention the purpose of Monday's exercises. While it is normal for the PLA to conduct exercises before anniversaries - such as that of its founding on Sunday - experts on the mainland and overseas agreed that the sheer scale of the drills was exceptional. Gary Li, a PLA analyst at the London-based International Institute for Strategic Studies, said the televised display of so many missile tests was highly unusual. 'It looks like [China] was clearly sending a message,' he said. 'I have never seen a senior Central Military Commission member actually participating in naval exercises, along with so many high-level officers. The deck of the observer ship was strewn with gold braid,' he said. The news was only reported yesterday by China Central Television and the Ministry of Defence on its website. PLA Chief of General Staff Chen Bingde and naval commander Wu Shengli - both members of the Central Military Commission - supervised the exercises. Flagships of all three naval fleets took part in the war games, indicating the scale of the operation. Xu Guangyu, a senior researcher of the China Arms Control and Disarmament Association, said the three fleets regularly carry out [separate] exercises to mark the PLA's founding anniversary. 'But of course, this time there is a strategic necessity to bring all three together for such a big joint mission,' he said. State media did not say exactly where the drills took place or how many ships or sailors participated. 'We must pay close attention to changes in [regional] situations and the development of our mission; prepare ourselves for military struggle,' Chen was quoted by the state media as saying. The military channel of China Central Television showed selected footage of the drills. Luyang-class destroyers, Sovremenny-class destroyers and guided-missile frigates carried out synchronised warfare manoeuvres and test-fired several types of ship-to-air and anti-ship missiles, the footage showed. The CCTV report said the navy focused on how to conduct a precise strike in a complex environment amid sophisticated enemy electronic jamming. 'It is a comprehensive and complex exercise in our history. The number of missiles fired and the intensity of the electronic warfare conducted are both remarkable.' Military exercises are an important feature of Chinese military doctrine and often offer an important strategic insight into the PLA's intentions and capabilities. Analysts are divided on the exact motive for the latest exercise but agreed that it was a show of defiance against US dominance in Asia. Li said the exercises were probably a further reaction to the ongoing US-South Korean manoeuvres in the East Sea, given their apparently high degree of organisation. Significantly, the PLA was showing off a comprehensive array of long-range attack capabilities, including missiles launched from submarines and fast-attack craft. 'It is a very strong message ... showing they can project force across a wide range of platforms in a very comprehensive and adaptable way,' he said. Antony Wong Dong, president of the Macau-based International Military Association, said the gathering of main forces of the three fleets in the South China Sea was to show China's concern over America's involvement in territorial disputes in the troubled region. Conducting such co-ordinated manoeuvres of ships from all three fleets is rare for the PLA and would take time to prepare. But recently, the PLA demonstrated it had mastered the required capabilities to bring a separated force together to carry out co-ordinated missions. In April, the PLA navy carried out elaborate long-distance exercises to the southeast of Japan's offshore islands. 'It's not that difficult for today's PLA navy to organise joint-fleet exercises at short notice,' Xu said. China's rapid growing military clout has raised concerns in the region, particularly among nations that have unsolved territorial disputes with Beijing. A senior Vietnamese military official warned on Wednesday against an arms race in the South China Sea, noting a growing naval presence from a range of nations, including China. Lieutenant General Nguyen Chi Vinh, deputy defence minister, said China's military exercises were its own affair but they must not interfere with the territorial integrity of Vietnam's holdings in the sea's Spratly islands. 'We never want to see an arms race in this area,' he said. Countries like Vietnam 'should be worried' if 'concerned parties do not find a common understanding and direction... and all want to impose their opinion on each other'.