NEW DELHI -- India is unlikely to swiftly replace its oil purchases from longtime ally Moscow amid global supply constraints even as a new U.S. sanctions measure threatens up to 100% tariffs on major buyers of Russian energy, analysts and officials say.

India imports more than 85% of its crude oil needs, of which Russia is a key source. According to United Nations data, Russia was India's top crude oil supplier in 2025, with a 33% share by value.

For Russia, India is a key oil market. A Sept. 10 report by the Centre for Research on Energy and Clean Air says India imported a total of 4.8 billion euros ($5.46 billion) worth of Russian hydrocarbons in August, making it the second-largest buyer of Russian fossil fuels, after China.

Crude oil, CREA says, made up 87% of India's purchases, totaling 4.1 billion euros, though these imports fell 24% from July's record high. The decline followed the U.S. Senate's overwhelming vote to approve the Lindsey O. Graham Sanctioning Russia and Iran Act (SRIA) of 2026, which penalizes Moscow and top buyers of its petroleum products, such as India and China.

President Donald Trump signed the bill into law on Sept. 18, leaving it to take effect within 30 days. The law authorizes and expands statutory sanctions, tariffs and prohibitions on Russia and extends existing sanctions on Iran.

"India should continue buying Russian oil as long as it remains commercially competitive and negotiate firmly without offering unilateral trade concessions" to the U.S., given that New Delhi and Washington have been negotiating a trade agreement since early last year, Ajay Srivastava, founder of the New Delhi-based think tank Global Trade Research Initiative, said in a note shared with Nikkei Asia.

The new U.S. law, which puts India at direct risk of tariffs of up to 100%, "may be used to pressure New Delhi to cut Russian oil purchases and accept an unequal bilateral trade agreement," Srivastava said. India "must not exchange long-term energy security and permanent trade concessions for temporary tariff relief." Prerna Gandhi, an associate fellow at India's Vivekananda International Foundation think tank, noted that India has become a "heavy buyer" of Russian crude because of its price advantage and Moscow's ability to supply large volumes.

"Replacing Russian crude quickly could raise India's import bill and domestic inflation, particularly when the Middle East is already facing supply and shipping disruptions and Brent is above $100 [per] barrel," she said.

Gandhi, however, observed that the U.S., too, has an interest in preventing the removal of millions of Russian barrels from the global market, especially during an already tight market. She added that India could negotiate for waivers or exemptions while making clear that its energy security is a national-interest issue. "Further, given the U.S. interest in setting up data centers in India, [the] energy security of India is also in the interest of the United States," she said.

Indian Finance Minister Nirmala Sitharaman recently shed light on why India cannot simply switch from Russia to other oil suppliers. "India can get out of Russia and say, 'Alright, I'm buying oil from somewhere else.' The moment you come out, the available pool, which is limited, is going to shoot up in price," she said during an event in New Delhi last week. Sitharaman also pointed out that India is already diversifying its oil basket to meet the country's energy needs.

She also underlined that Indian refineries are suitable for processing medium-sour crude in terms of density and sulfur content. "But, if we have to pick it up from somewhere else where it is available [and] which ... even with some tweaking, cannot be treated by our refineries, what good is that for? And whose cause are we then serving? So, we need to be practical." "It poses a severe challenge, no doubt, but I think we will have to keep India's interest topmost," Sitharaman said.

Her comments followed India's Ministry of External Affairs' statement that the latest U.S. measure could have "potential implications for not just the bilateral relationship but also the international energy market" and that New Delhi has "very clearly articulated" this in discussions with Washington.

The matter came up when India's External Affairs Minister S. Jaishankar and U.S. Secretary of State Marco Rubio met in New York last Wednesday. Jaishankar posted on X that he "reiterated India's interests and concerns with regard to SRIA" and also discussed the Gulf and Ukraine situations with Rubio.

The U.S. readout said the two discussed sanctions that could be leveled against states that engage economically with Russia and Iran. "The Secretary emphasized that the United States remains well-positioned to help regional partners address their energy security challenges," the statement said.