NEW DELHI - Russian President Vladimir Putin arrives in India Monday for a summit as Moscow begins the delivery of air defense missile systems to India that could spur U.S. sanctions.

India's $5.4 billion deal with Russia to purchase S-400 air defense missile systems highlights New Delhi's challenge in maintaining its partnership with Moscow, even as it embraces closer strategic ties with the United States.

While Washington has often warned New Delhi that the purchase of five long range surface-to-air missile systems from Russia runs counter to 2017 U.S. legislation, India's consistent message has been that its national security interests guide its defense purchases.

"The government takes sovereign decisions based on threat perceptions, operational and technological aspects to keep the armed forces in a state of readiness to meet the entire spectrum of security challenges," Minister of State for Defense Ajay Bhatt told Parliament Friday.

India says it needs the S-400 system to counter the threat from China - it is expected to be deployed along disputed Himalayan borders where troops from both countries have been locked in a standoff since last year.

FILE - First parts of a Russian S-400 missile defense system are unloaded from a Russian plane near Ankara, Turkey, July 12, 2019.

Washington imposed sanctions on Turkey last December for purchasing the same missile system from Russia under the Countering America's Adversaries Through Sanctions Act, whose aims include deterring countries from buying Russian military equipment.

New Delhi however is optimistic about getting a presidential waiver, as its strategic ties with the United States continue to gain momentum in the two countries' common efforts to contain China's assertiveness in the Indo-Pacific region - India is part of the Quad group expected to play a key role in countering China.

Potential waiver

U.S. State Department spokesman Ned Price told a November 23 briefing that the Biden administration has not decided on a potential waiver for India, but analysts in Washington say a waiver is inevitable.

"The Biden administration doesn't want to do anything that would risk imperiling its relations with New Delhi. Sanctioning India would plunge bilateral relations to their lowest point in several decades," Michael Kugelman, deputy director of the Wilson Center in Washington, said.

However, he said, a waiver for India would be a one-time affair.

"It won't offer any blanket free passes to New Delhi on its broader defense trade with Moscow. So, the Russia factor will remain a rare tension point in U.S.-India relations," he said.

Strategic affairs experts point out that while India and Russia have pulled in different geopolitical directions, New Delhi is not ready to dismantle its security relationship with a Cold War ally that remains a key defense supplier.

"For India, China is the No. 1 adversary, whereas for Russia, China is a partner. And for Russia, the main adversary is the U.S., with which India's ties are growing. So, there is a significant mismatch in terms of our perceptions in where our threats originate from," said Rajeswari Pillai Rajagopalan, director of the Centre for Security, Strategy and Technology at the Observer Research Foundation in New Delhi.

"However, India needed the S-400 system to boost its military capabilities and it was available at a reasonable price," she said.

A rare overseas trip

The Monday summit marks a rare overseas trip for Putin since the COVID-19 pandemic - he has left Russia only once, to meet U.S. President Joe Biden in June.

FILE - US President Joe Biden and Russia's President Vladimir Putin meet at Villa La Grange in Geneva, Switzerland, June 16, 2021.

The defense and foreign ministers of the two countries will also meet in New Delhi. The summit is expected to the signing of 10 agreements that could include U.S. purchase of assault rifles to be made in India and renew a framework for military technical cooperation. India's ambassador to Russia, Venkatesh Verma, told the Tass news agency last month that India could also order fighter jets and tanks.

While India has moved away from its heavy dependence on Russian equipment in recent decades by significantly increasing acquisition of military equipment from countries like the United States, France and Israel, Russia remains India's largest weapons supplier.

"It is more of a business relationship with Russia than a strategic partnership. We understand how close Russia is with China, but we need critical military equipment such as the S-400 missile systems," according to Chintamani Mahapatra, rector and professor of American studies at Jawaharlal Nehru University in New Delhi.

India hopes that its ties with Russia will also help it in playing a role in Afghanistan, where its rivals China and Pakistan are now key players.

Analysts say that maintaining relations with Moscow is important for New Delhi to underline that it is not too closely aligned with any one country.

"We don't want to be seen as completely in the U.S. or Western camp. So we want to keep the Russia relationship alive," Pillai said.

Russia, for its part, is also uneasy about India's deepening security ties with the United States, especially New Delhi's participation in the "Quad" - the alliance among the United States, Japan Australia and India. Moscow has said it opposes the creation of security blocs in the Asian region.

"India-Russia partnership is a potential obstacle for the Quad, but not a major one," according to Kugelman who said that amid a growing China-Russia relationship, "the geopolitical signposts all point to reduced India-Russia partnership in the coming years."