India awarded this week a major contract to Boeing. The U.S. company inked a contract with India for four more P-8I maritime surveillance aircraft for the country's navy, Defense News reported

An anonymous defense official told the news outlet that the deliveries are expected to be completed within the next three years. The Indian Navy — which was the first international customer for the P-81 aircraft — is already in possession of eight of the aircraft. The P-81, in Boeing's words, is an "anti-submarine warfare, anti-surface warfare, intelligence, surveillance and reconnaissance aircraft." India's eight P-81 are equipped with Harpoon missiles,  lightweight torpedoes and rockets.

The latest purchase was actually an option in the previous deal, which India chose to exercise. The decision was followed a visit to India by Frank Kendall, the Pentagon’s top acquisition official.

"The Indian Navy has been clear about their intent to exercise these options," Boeing spokeswoman Caroline Hutcheson told USNI News. "We will defer to the MoD for any formal announcement."

The earlier contract for eight planes signed in January 2009 was worth $2.1 billion. The new deal between India and Boeing is just the latest in a recent uptick in military expenditures between the South Asian nation and the United States. The Stockholm International Peace Research Institute found India's arms imports from the U.S. during 2010-2015 were 11 times the amount during the five years prior, via the Wall Street Journal.

"The latest acquisition of the P-8I is a milestone in India’s strategy to replace its aging equipment, much of which was bought from Russia during the Soviet era," wrote the Wall Street Journal. "The twin-engine jet has a range of about 2,222 kilometers, or more than 1,200 nautical miles, which allows the Indian navy to monitor the country’s vast coastline."

India is expected to continue its efforts to upgrade it military under the direction of Prime Minister Narendra Modi. The country has plans to purchase howitzers, warships, submarines and fighter jets.