New Delhi is expected to purchase two dozen unarmed drones from the United States to monitor growing Chinese activity in the Indian Ocean.

President Donald Trump’s administration authorized the sale in June, with the price tag estimated at $3 billion, according to defense researcher Jane’s by IHS Markit. The U.S. approval was the first such clearance to a friendly, non-NATO nation, but the transaction has yet to be finalized and was a key topic of discussion during General James Mattis‘ visit to India this week.

Manufactured by American defense contractor General Atomics, the unmanned devices— called Guardians — are “the world’s most advanced maritime reconnaissance drones and can help India track the movement of Chinese warships with its multi-mode maritime radar,” said Harsh Pant, head of the strategic studies program at the Observer Research Foundation, a New Delhi-based think tank.

Privately held General Atomics makes the drone in question as a maritime variant of its Reaper unmanned vehicle.

The world’s second-largest economy has ratcheted up maritime patrols around the Indian Ocean, which is home to seaborne routes crucial to global trade as well as a major U.S. military base. The mainland has also built up a presence in other countries around the region.

July saw Beijing establish its first overseas naval base in Djibouti, located on the ocean’s northwestern side. That same month, state-owned China Merchant Port Holdings acquired Sri Lanka’s Hambantota Port, which juts out into the strategic waterway, in a move expected to facilitate Chinese naval deployments. It’s a similiar story in Bangaldesh, where state-owned enterprise China Harbour Engineering Company bought a majority stake in Payra Port, located at the southern-most tip of the country. The mainland is also looking to take an 85 percent stake in Myanmar’s deep sea port of Kyauk Pyu on the Bay of Bengal, according to reports.

Occuring right in India’s backyard, these projects — part of China’s massive “Belt and Road” infrastructure program — are a worrying development for New Delhi, which has long held sway as the region’s major power and comes just weeks following the end of a Sino-Indian border dispute in the Himalayas.

As a result of increasing Chinese influence, Prime Minister Narendra Modi’s government has been taking steps to boost its capabilities in the Indian Ocean, reflected by initiatives such as the Guardian drone purchase.

All that comes amid Beijing’s use of underwater drones in the South China Sea, a separate body of water where President Xi Jinping’s administration is trying to enforce a tremendous, 1.4-million square mile claim despite losing a legal case on that claim last year.

“Unmanned vehicles, like those whose sale has been proposed by the United States, would allow India to monitor activities in the region much better … Clearly, there are concerns about the militarization of the Indian Ocean, including the increased presence of China’s People’s Liberation Army Navy,” explained Dhruva Jaishankar, foreign policy fellow at Brookings India.

Those worries are shared by the White House, which remains wary of China’s intentions in the Asian region. Speaking on Wednesday, General Joseph Dunford, chairman of the U.S. Joint Chiefs of Staff, said a security relationship with New Delhi was critical to ensuring freedom of navigation in the Indian Ocean.

China was the main factor behind Washington’s approval of the Guardian drone sale, noted Pant of the Observer Research Foundation.

India’s air force has also requested for 90 armed Avenger Predator drones, also produced by General Atomics, that many believe could be used for cross-border strikes on Pakistani militants in the Kashmir conflict.

“Armed drones can be used for a number of functions, including counter-terrorism activities,” said Jaishankar. “The U.S. has used them quite effectively against groups in Pakistan and Afghanistan.”

However, the sale of armed drones is subject to approval by U.S. Congress members who retain concerns about intellectual property and the danger of misuse by third parties, Jaishankar warned.