China and India are closely watching the constitutional crisis in Sri Lanka, which has been a battleground in their struggle for geopolitical supremacy in South Asia.Chinese and Indian diplomats have been careful not to overtly take sides in the political turmoil, which has seen President Maithripala Sirisena oust Prime Minister Ranil Wickremesinghe, replace him with former strongman Mahinda Rajapaksa, and suspend Parliament.Wickremesinghe, meanwhile, has holed up at the prime minister's residence and insisted he is Sri Lanka's rightful leader.The caution exercised by the Asian giants stands in contrast to calls from Western diplomats for Parliament to immediately be summoned for a floor vote on Rajapaksa's appointment and underscores the economic and military importance the countries place on the Indian Ocean island nation."They're hedging their bets," said Bharath Gopalaswamy, director of the Atlantic Council's South Asia Center. India and China "both have stakes in the global system and want to play a bigger role, so they have to signal they'll work with whomever."For China, Sri Lanka is a critical link in its massive Belt and Road Initiative, which aims to use infrastructure projects to expand trade across a vast arc of 65 countries from the South Pacific through Asia to Africa and Europe. It has handed out billions of dollars in loans for Sri Lankan projects over the past decade.Located just 23 kilometers (14 miles) off its southeast coast, India sees Sri Lanka as a bulwark in its military defenses to ward off potential Chinese incursions and also sees the island as a key partner for regional trade. India has grown wary of China's economic influence over Sri Lanka and was troubled by a 2014 port visit from a Chinese submarine and warship.Sri Lanka's ties to both nations date back thousands of years. It was a stop along China's old Silk Road trade routes, where merchants picked up pepper, cinnamon, ivory and pearl.Sri Lanka traces much of its genealogy and culture to India, with folklore saying the island's majority Sinhalese are descendants of an Indian prince banished there 2,000 years ago.The nation's minority Tamils, meanwhile, are in part the descendants of more than a million tea and rubber plantation workers brought to Sri Lanka from southern India by British colonial rulers in the 18th and 19th centuries.Yet that hasn't always led to smooth relations. During Sri Lanka's decadeslong civil war, which pitted Tamil rebels against the government, India intervened in the 1980s by sending a peacekeeping force that quickly found itself engaged in battle with the rebels. They were asked to withdraw a few years later amid allegations of abuses against Tamils.China filled the vacuum left by India, providing military assistance that helped the Rajapaksa-led government defeat the rebels in 2009. In 2012, China helped block a UN Human Rights Council resolution demanding that the Sri Lankan government investigate war crimes. It would later pass, but it prompted little action by Rajapaksa, who was in power from 2005 to 2015.China is partly involved in the current crisis because of tensions over the billions of dollars of loans it has given to build a network of highways, the Hambantota seaport and airport in Rajapaksa's home district, and other projects. The most iconic of these has been the $1.5 billion port city being built on reclaimed land off Colombo's coast.Sri Lanka's debt more than tripled during Rajapaksa's presidency, Sri Lankan Central Bank figures show.New Delhi and other international critics have called the loans a debt trap.Central bank figures , however, show that Sri Lanka's debt to India stood at 145 billion rupees (about $19.9 billion) in 2017 versus 135 billion rupees (about $18.5 billion) owed to China the same year.Rajapaksa's defeat at the polls in 2015 was partly a reaction to all of that debt, said Gopalaswamy, the analyst.Likewise, Wickremesinghe, prime minster from 2015, saw his popularity begin to wane last year after his government handed over operations of the Hambantota port to a Chinese company in a 99-year lease."From a democracy perspective, there's been huge public resentment because the quality of these projects is questionable, there's little parliamentary scrutiny and no one knows where this money ends up," Gopalaswamy said.Responding to public outrage over the lease, China in July offered Sirisena a nearly $300 million grant that the president said could be used "for any project of my wish."With so much at stake, the Chinese ambassador to Sri Lanka, Cheng Xueyuan, was among the first to congratulate Rajapaksa after he was appointed prime minister on Oct. 27. But that day, Cheng also visited Temple Trees, the official prime minister's residence, where Wickremesinghe has been holed up since his ouster.China's Foreign Ministry spokesman Lu Kang said that Cheng's visits to rival prime ministers was simply part of China's policy of maintaining "friendly exchanges will all parties in Sri Lanka," repeating China's routine assertion that it doesn't interfere in the internal affairs of other countries.But after the surprise win of an opposition candidate in the Maldives who campaigned on a promise to reduce China's role in the Indian Ocean archipelago nation, Sri Lanka's strategic position has increased. If projects in the Maldives are canceled, Sri Lanka would be China's main Indian Ocean link between Asia and the Seychelles, off the coast of East Africa.A spokesman for Sri Lanka's new government, Kehaliya Rambukwella, said Rajapaksa had spoken to Chinese officials about revising the terms of the Hambantota port lease.New Delhi doesn't have many options for how to respond to the crisis, said G. Parthasarthy, a retired Indian diplomat and an expert on Sri Lanka affairs."We would like to see South Asia integrated much more closely with India, so we cannot be seen as taking sides," Parthasarthy said, adding that India's Prime Minister Narendra Modi hosted both Rajapaksa and Wickremesinghe in separate visits to New Delhi last month.The day after his ouster, Wickremesinghe met with Colombo-based diplomats from the US, Britain, Australia, the European Union and India, among others. Many issued statements calling for the country's constitution and democracy to be respected. Sirisena held his own meeting with foreign diplomats on Oct. 29.Wickremesinghe said he hasn't received any official support from foreign powers, nor has he sought any."I agree with them that the constitution must be followed," he said.Since the crisis began, constitutional scholars have argued over whether Sri Lankan law allowed the president to remove the prime minster and appoint someone new.Sirisena on Sunday ordered Parliament to reconvene Nov. 14 for a confidence vote on Rajapaksa. China and India will be closely watching to see if the vote eases or exacerbates the crisis.