India's cabinet has approved the purchase of 22 Apache attack helicopters and 15 CH-47 Chinook helicopters made by U.S. manufacturer Boeing for $2.5 billion.

The 37 new helicopters are to replace India's aging Soviet-era aircraft. The Indian Air Force tapped both aircraft for purchase in 2012, but India's budget did not yet allow for a transaction.

India faces considerable pressure to modernize its air fleet. According to the International Institute for Strategic Studies, a U.K.-based think tank, about 79 percent of the country's aircraft squadrons are Soviet designs, remnants of India's relationship with the USSR during the Cold War.

In July this year, Boeing and India's and Tata Advanced Systems Ltd entered an agreement to collaborate on aerospace and defense manufacturing and opportunities in integrated systems development.

"It is noteworthy that TASL will produce Chinook helicopter parts in India even before the procurement contract is signed with the Indian government," Pratyush Kumar, president of Boeing India, said in a statement at the time.

The 22 Apache AH 64D Longbow is an advanced multi-role combat helicopter, and is designed to perform under extreme weather conditions.

The deal marks the latest push by U.S. industry into India's security market. U.S.-based companies including Boeing have signed over $10 billion in defense contracts in the country over the last decade.

The deal comes as Boeing announces a 'India's Time to Fly', an aerospace innovation summit scheduled for October 16. The event is part of a series of forums intended to celebrate Boeing's upcoming centennial in 2016.