NEW DELHI - India is exploring ways to avoid a major disruption in its supply of Russian-made weaponry amid U.S. sanctions following Moscow's invasion of Ukraine, and Prime Minister Narendra Modi's tightrope walk could become more difficult due to a continuing border standoff with China.

Experts say up to 60% of Indian defence equipment comes from Russia, and New Delhi finds itself in a bind at a time when it is facing a two-year-old standoff with China in eastern Ladakh over a territorial dispute, with tens of thousands of soldiers within shooting distance. Twenty Indian soldiers and four Chinese soldiers died in a clash in 2020.

"The nightmare scenario for India would be if the U.S. comes to the conclusion that it confronts a greater threat from Russia and that this justifies a strategic accommodation with China. In blunt terms, concede Chinese dominance in Asia while safeguarding its European flank," Shyam Saran, India's former foreign secretary, wrote in a recent blog post.

Would China, drawing lessons from Ukraine, be an aggressor in disputed eastern Ladakh or in Taiwan?

"It is very possible they might do it," said Jitendra Nath Misra, a retired diplomat and distinguished fellow in the Jindal School of International Affairs.

President Joe Biden has spoken about unresolved differences with India after the country abstained from voting on United Nations resolutions against Russian aggression in Ukraine. Modi has so far avoided voting against Russia or criticizing Putin for invading Ukraine.

In the early 1990s, about 70% of Indian army weapons, 80% of its air force systems and 85% of its navy platforms were of Soviet origin. India is now reducing its dependency on Russian arms and diversifying its defence procurements, buying more from countries like the United States, Israel, France and Italy.

From 2016-20, Russia accounted for nearly 49% of India's defence imports while French and Israeli shares were 18% and 13%, respectively, according to the Stockholm International Peace Research Institute.

India not only depends on Russian weaponry, but it also relies hugely on Moscow for military upgrades and modernization as it moves toward self-reliance in its defense sector, said Lt. Gen. D.S. Hooda, a former Indian military commander.

"Russia is the only country that leased a nuclear submarine to India. Will any other country lease India a nuclear submarine?" Hooda asked.

Sushant Singh, a senior fellow at the Centre for Policy Research, said: "India's navy has one aircraft carrier. It's Russian. India's bulk of fighter jets and about 90% of its battle tanks are Russian."

In 1987, the Indian navy leased a Chakra-1, a Charlie-class nuclear cruise missile submarine, from the former Soviet Union for training. It later got another Soviet submarine, Chakra-2, in its place. In 2019, India signed a $3 billion contract to lease an Akula-1-class nuclear-powered attack submarine from Russia for 10 years. It is expected to be delivered by 2025.

India bought its only aircraft carrier, INS Vikramaditya, from the Russia in 2004. The carrier had served during the former Soviet Union and later for the Russian navy. India's first indigenous 40,000-tonne aircraft carrier is undergoing sea trials ahead of its planned induction by next year.

India also has four nuclear-powered ballistic missile submarines on the way.

India's air force presently operates more than 410 Soviet and Russian fighters, comprising a mix of imported and license-built platforms. India's inventory of Russian-made military equipment also includes submarines, tanks, helicopters, submarines, frigates and missiles.

Misra said the U.S. hasn't shown any willingness to provide technology transfers to India.

"I would like to ask our American friends: What kinds of defence technology have you given us? What the U.S. is offering is the F-16 fighter aircraft rebranded as the F-21. The F-16 is obsolete from the Indian point of view. We went for the MiG-21 in the 1960s because the F-104 was denied to India. We are seeing the same kind of thing,'' he said.

"Under the AUKUS agreement, the U.S. is willing to share the nuclear propulsion technology for submarines with Australia but is not willing to share it with India," he added, referring to the trilateral security pact between the U.S., U.K. and Australia.

Australia in September decided to cancel a multibillion-dollar contract to buy diesel-electric French submarines and said it would instead acquire U.S. nuclear-powered vessels in a new Indo-Pacific defence deal under AUKUS.

During the Donald Trump presidency, the U.S. and India concluded defence deals worth over $3 billion. Bilateral defence trade increased from near zero in 2008 to $15 billion in 2019. Major Indian purchases from the United States included long-range maritime patrol aircraft, C-130 transport aircraft, missiles and drones.

As the Ukraine crisis deepens, the challenge for India is how to navigate international sanctions against Russia.

The Russian S-400 missile system deal with Moscow has put India at risk of U.S. sanctions after Washington asked its partners to avoid purchasing Russian military equipment. The S-400 is a sophisticated surface-to-air defence system and is expected to give India strategic deterrence against rivals China and Pakistan.

New Delhi has sought support from Washington and its allies in confronting China, a common ground for the Indo-Pacific security alliance known as "the Quad" that also includes Australia and Japan.

Tracing the history of India's acquisition of Soviet arms, SCS Bangara, a retired navy admiral, said India began looking for arms and ammunition after its war with China in 1962.

The Cold War resulted in the United States cosying up with China. Pakistan as a facilitator held a trump card that could be used to enlist the complete support of the U.S. government in the event of an India-Pakistan conflict, he said.

During India's war with Pakistan in December 1971 that led to the creation of Bangladesh, the U.S. deployed a task force led by the USS Enterprise in the Bay of Bengal in support of Pakistan.

In the mid-1960s, India negotiated a series of acquisition agreements with the Soviet Union that continued for the next 40 years, Bangara said.

"It was not seamless, particularly when the Soviet Union collapsed. The long chain of training facilities along with the supply chain of logistics collapsed when the Union broke into smaller states," he said.

Even as India diversifies its defence acquisitions from the U.S., Israel, France and other countries, it may take 20 years to get over its dependence on Russian supplies and spares, Bangara said.