From Tanzania to Sri Lanka, the two Asian heavyweights are trying to establish a stronger military and economic presence in countries along the Indian Ocean in a quest for regional supremacy.
China, the world's second biggest economy, is looking to build what some policy experts call a "string of pearls" — a network of defense and commercial facilities — around the massive area. Beijing in 2016 revealed plans to launch its first overseas military base in Djibouti. Numerous business projects by state-owned Chinese enterprises under President Xi Jinping's massive Belt and Road program, which includes a port in Tanzania, have reinforced its efforts.
New Delhi, unsettled by the thought of Beijing dominating its own backyard, is responding in kind.
On a visit to Oman last month, Prime Minister Narendra Modi secured access to naval facilities in the Middle Eastern state, which is near the Strait of Hormuz. More than 30 percent of seaborne oil exports pass through that narrow waterway daily.
Earlier this year, India signed a 20-year pact with the Seychelles to build an airstrip and a jetty for its navy. Last November, Modi's team inked a pact with Singapore that may boost Indian access to that country's Changi naval base.
"It seems that we are in the middle of a base race across the Indian Ocean," David Brewster, senior research fellow at at the Australian National University, wrote in a February note published on think tank The Lowy Institute. "Watch this space."
The Indian Ocean, which borders Africa, the Middle East, Asia and Australia, is home to major sea lanes and choke points that are crucial to global trade. Nearly 40 percent of the world's offshore petroleum is produced in the Indian Ocean, which also has rich mineral deposits and fisheries.
Commercial projects undertaken by Indian and Chinese companies could also be put to military purposes.
When China Merchants Port Holdings signed a 99-year lease on Sri Lanka's Hambantota Port in July, worries emerged that China's navy would make use of the facility despite Sri Lanka's assurances to the contrary. A few months later, Reuters reported that New Delhi was looking to take over Hambantota's local airport.
Indian and Western diplomats "are convinced that Hambantota will end up becoming a Chinese military and naval base, or another Djibouti," the Observer Research Foundation, an Indian think tank, said in an October report.
"Future military uses of Chabahar by India cannot be ruled out," said Brewster. The $85 million Chabahar project, located only about 350 kilometers from Gwadar, is aimed at creating a transit route between India, Iran and Afghanistan.
The Indian Ocean has also become a hotspot for weapons technology.
Beijing plans to deploy sea-based anti-missile systems there, according to recent reports. And analysts said New Delhi's 2017 request for U.S. aerial drones was aimed at monitoring Chinese activity in the ocean.