Speaking at the Shangri-La Dialogue in Singapore, Mattis said the US' stance is partly "out of respect for India's indispensable role in maintaining stability in the Indian Ocean region."
The statement demonstrates America's strategic outlook towards India and the important role defense cooperation plays in Indo-US ties.
A look at Indo-US defense ties
India's arms purchases with US picked up after 2001
Through much of the Cold War and thereafter, India didn't purchase defense equipment from the US as bilateral relations remained poor.
Increased bilateral trade post-9/11 led to a larger convergence of interests which resulted in the 2004 Strategic Partnership Agreement.
In 2005, India and the US signed the defense framework agreement. Since then, India has purchased military equipment worth over $10 billion from America.
Why is US selling weapons to India?
The US' decision to sell weapons to India are driven by both business and strategic considerations.
India is the world's largest arms importer while America is the largest exporter. India being a billion dollar arms market represents a huge opportunity for the US arms industry.
The US is also attempting to strategically arming India as a regional military counter-balance to the increasingly assertive China.
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India has purchased $8 bn worth of aircraft from US
Among the major military platforms sold to India, the most advanced and expensive are six Lockheed Martin C-130 transport aircraft worth $1 billion, 10 C-17A Globemaster-III heavy transport aircraft ($4.1 billion) and 12 P-8I Poseidon maritime patrol aircraft ($3 billion).
US engines power India's Tejas warplane, indigenous aircraft carrier
The US-based General Electric's GE-404 jet engine powers India's indigenous Tejas fighter jet.
General Electric's LM-2500 gas turbine engines propel the Indian Navy's indigenous Shivalik-class stealth frigates and Vikrant-class aircraft carrier.
The Indian Navy also possesses INS Jalashwa, a second-hand American amphibious transport dock.
The Indian army recently inducted the first of 145 M777 howitzers bought from US-based BAE systems worth $660 million.
American choppers for IAF to be partly made in India
In 2015, India signed a $3 billion deal with Boeing for 22 stealthy and deadly Apache attack helicopters and 15 Chinook heavy-lift choppers for the Indian Air Force. Boeing is collaborating with Tata Advanced Systems to jointly produce aerostructures for the Apache helicopter.
US offers F-16 and F/A-18 fighter jets to IAF, navy
US-based aerospace major Lockheed Martin is fervently pitching its F-16 combat jets for the IAF's requirement for around 100 single-engine warplanes. It has proposed manufacturing the warplanes in India under the 'Make in India' program.
Boeing is also pushing for the F/A-18 warplane for the IAF and the Indian Navy's recent request for information for 57 aircraft carrier-borne fighter planes.
US-Pakistan ties worsen, military aid declines 73%
The US has for decades been the biggest source of sophisticated arms and military aid for Pakistan. This has angered India as these arms have been used against it.
However, US-Pakistan ties have become increasingly strained in recent times.
US military aid to Pakistan has dropped 73% from nearly $1.3 billion in 2011 to $343 million in 2015, according to the Congressional Research Service.
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