NEW DELHI: India is desperate to buy five S-400 long-range surface-to-airmissile systems from Russia that the country`s military sees as a gamechanger. The systems are touted as being able to counter the ballisticmissiles and stealth aircraft that China is developing, while overwhelmingthe capabilities of Pakistan, India`s main adversary.

India is frustrated after the latest US sanctions which hinders its way toget the long desired technological edge over Pakistan in missile field which only S-400 missile defence system could have given it.

U.S. sanctions on Russian military exports have put the brakes on a $6billion deal with India and may derail the arms purchases of other U.S.allies around Asia, experts say.

Under a law that U.S. President Donald Trump signed in August, any countrytrading with Russia`s defence and intelligence sectors will face sanctions.

The law is designed to punish Russian President Vladimir Putin for the 2014annexation of Crimea from Ukraine, involvement in the Syrian civil war andmeddling in the 2016 U.S. presidential election.But American allies who buy weapons and equipment from Russia, the world`ssecond-largest arms exporter, could suffer as well.

The deal, which Putin and Indian Prime Minister Narendra Modi struck aspart of an inter-government agreement in 2016, has run headlong into theU.S. sanctions law, two officials in Delhi said.

Indonesia and Vietnam also buy weapons from Russia while being regionalpartners of the United States. Jakarta closed a $1.14 billion pact forSukhoi fighters recently, while Vietnam is seeking more jet fighter-bombersfrom Russia.

And with both Almaz-Antey Air and Space Defense Corporation, which makesthe S-400, and Rosoboronexport, which negotiates Russian export deals,listed as under sanction, those deals have become trickier.

“The optics of a major arms purchase from Russia looks quite `iffy` fromthe point of view of Western capitals, especially at a time whenRussia-West relations are at an all-time low and India seeks strategicconvergence with the West, including with the U.S.” said Abhijnan Rej, adefence strategy expert at Observer Research Foundation, a New Delhi thinktank.

The U.S.-led airstrikes this month against facilities of the Syriangovernment, an ally of Russia, has further aggravated tensions between thesuperpowers.