India has inked a $3 billion agreement to lease a third Russian nuclear-powered submarine for 10 years, giving its navy a boost in the Indian Ocean against arch-rivals Pakistan and China, according to media reports.

The deal – which according to the reports took months to negotiate – comes as tensions are running high between India and Pakistan following their most dramatic standoff in years, and as the regional influence of China grows.

A Defense Ministry spokesman declined to confirm the agreement to AFP but the reports said that the submarine would be delivered by 2025.

Russia, India’s Cold War ally, remains a major supplier of arms to India, irking Washington, which has imposed sanctions on countries purchasing military hardware from Moscow.

Last October, Russian President Vladimir Putin and Indian Prime Minister Narendra Modi met and signed an agreement for Delhi to buy Russia’s S-400 surface-to-air missile defense system for $5.2 billion.

New Delhi also shares Washington’s concerns about China’s growing assertiveness in the Indian Ocean, where India has traditionally been the dominant actor.

– with reporting by Agence France-Presse