India and the United States have inked the largest-ever bilateral defence deal, worth 4.1 billion U. S. dollars, under which Washington will deliver some 10 C17 Globemaster-III strategic airlift aircraft to New Delhi within four years, local media reported Thursday.

As per the "letter of offer and acceptance" inked between India and the U.S., Globemaster-manufacturer Boeing will also establish a high-altitude engine test facility as well as a trisonic wind tunnel facility at India's Defence Research and Development Organization for testing and research and development of aeroengines and aerodynamic bodies, The Times of India newspaper reported.

Cleared by the Indian Cabinet Committee of Security earlier this month, the deal will also entail Boeing ploughing back 1 billion U.S. dollars into India as the offsets obligation.

"This will include Boeing purchasing some products and services from public and private Indian defence industries," an official was quoted as saying.

The Globemaster, capable of carrying a maximum payload of 77.5 tons, including combat vehicles, artillery guns and battle-ready troops, will bolster India's swift power projection capabilities in its "primary area of geo-strategic interest", the report said.