Why is India interested in Russian missile system?

After signing the missile defense agreement, Indian Prime Minister Narendra Modi and Russian President Vladimir Putin said in a joint statement that ties between New Delhi and Moscow are going "from strength to strength." It was the third time this year that Modi and Putin have held talks.

The Russian-built S-400 surface-to-air missile defense system acts as a shield against incoming ballistic missiles. It is considered to be one of the world's most state-of-the-art, long-range, surface-to-air missile systems.

The Indian military wants to deploy missile batteries both as deterrent against China and also to gain an edge over another regional rival, Pakistan. With the help of this system, India can track and shoot down combat aircraft, even stealth planes, from long ranges.

India is also planning to acquire 4 Krivak-class frigates from Russia. Two of these warships will be assembled at Goa shipyard, whereas the rest will be bought ready-made from Russia. The Indian navy already has six similar frigates.

The United States has warned that countries signing agreements with Russia's defense and intelligence sectors will face heavy sanctions under the Countering America's Adversaries Through Sanctions Act (CAATSA), which President Donald Trump signed into law in August, last year.

More than 80 percent of India's military equipment came from the former Soviet Union during the Cold War. Since the 1990s, India has diversified its weapons purchase. The US is now one of India's top arms suppliers, closing $15 billion worth of deals in the past ten years.

The US has imposed sanctions on the Chinese military for its purchase of combat fighters as well as the S-400 missile system from Russia. India was hoping to get a waiver on CAATSA sanctions but the Trump administration is not ready to give any concession to its ally.