evidence: Pedra Branca’s location – 24 nautical miles east of Singapore and eight nautical miles south of Johor – is seen as strategic as it lies in the eastern approach to a key sea channel leading to the island nation from the South China Sea. [...] The second document was a naval report from the same year that suggested a British naval vessel assigned for Singapore’s protection regarded Pedra Branca as Malaysian territory. And the third was a map from 1962, but with handwritten notes from 1966 – a year after Singapore attained independence – that depicted Pedra Branca as outside the island nation’s territorial waters. [...] One possible reason for Malaysia’s decision to challenge the sovereignty of Pedra Branca despite the risk to bilateral relations, some observers say, could be the powerful Johor monarchy’s repeated insistence that the isle belongs to it.