Indonesia will sharply strengthen security around its South China Sea islands where there have been clashes with Chinese vessels, the defence minister said today, a day after Beijing's claims in the waters were declared invalid. In an interview with AFP, Ryamizard Ryacudu said bolstering defences around Indonesia's Natuna Islands would involve deploying warships, an F-16 fighter jet, surface-to-air missiles, a radar and drones, as well as constructing new ports and improving an airstrip. The military build-up, which started in recent months, would be completed in "less than a year", he said. "This will be our eyes and ears," the retired general said. "So that we can really see what is happening in the Natunas and the surrounding area in the South China Sea." His comments came after a UN-backed tribunal in The Hague ruled yesterday against China's expansive claims in the South China Sea, finding in favour of a challenge from the Philippines which has long-running territorial disputes with Beijing in the waters. The surprisingly strong ruling provided ammunition for Manila and other claimants locked in disputes over the resource-rich sea but sparked fury from Beijing, which warned its rivals against turning the waters into a "cradle of war" and threatened an air defence zone. Unlike several of its Southeast Asian neighbours, Indonesia has long maintained it has no maritime disputes with China in the South China Sea and does not contest ownership of any territory. But Beijing's claims overlap Indonesia's exclusive economic zone - waters where a state has the right to exploit resources - around the Natunas, and there has been an upsurge in clashes between Indonesian patrol and navy boats and Chinese fishing vessels and coastguards. The increase in high-seas confrontations has been triggered by Indonesian authorities' aggressive crackdown on illegal fishing in its vast waters. After a clash last month, President Joko Widodo visited the Natunas on a warship with his cabinet to send a message to China that Jakarta is serious about defending the remote archipelago. As well as the military hardware, Indonesia will send special air force and marine task forces as well as an army battalion to the Natunas, once barracks and housing have been built, Ryacudu said.