India, one of the largest defense buyers in the world, has finalized a $2.5 billion deal to buy attack and heavy transport helicopters from Boeing Co., ahead of Prime Minister Narendra Modi’s visit to the United States later this week.

India's cabinet committee on security cleared the agreement to purchase 22 Apache attack helicopters and 15 Chinook heavy-lift choppers, according to a Press Trust of India report Tuesday. The deal -- for the multi-role combat helicopters that have seen combat in Afghanistan, and are capable of operating at night and engaging multiple targets, and the transport helicopters -- was being negotiated since 2013, according to PTI. A report from Reuters, citing two government sources it did not name, said the deal would boost defense ties with the U.S. 

The deal involves one contract with Boeing for the helicopters and another with the U.S. government for the related weapons, radars and electronic warfare systems, according to the report. India also has the option to buy an additional 11 Apache fighter copters and four more Chinooks, according to the report.

Modi's government has stepped up defense purchases, including Rafale fighter jets from France's Dassault Aviation SA, and attack drones from Israel. And the latest agreement adds to about $10 billion in defense contracts that American companies have bagged from India over the last decade, the PTI report added. These include the acquisition of P-8I maritime surveillance planes, C-130J Super Hercules and C-17 Globemaster-III transport aircraft. 

The Indian leader will be in the U.S. on a five-day visit starting Sept. 24, and his itinerary includes the U.N. General Assembly in New York and Silicon Valley.