Indian Prime Minister Narendra Modi is being keenly watched by his Western allies as he meets Russian President Vladimir Putin in Moscow on his first foreign trip since he returned to office for a third term in June.

Mr Modi landed on Monday, just hours after Russian bombing killed at least 41 people in Ukraine, including at a children's hospital in Kyiv, sparking a global outcry.

Photos from Moscow showed a beaming Mr Modi hugging the Russian president. A video of a smiling Mr Putin calling Mr Modi "my dearest friend" and telling him that he was "delighted to see him" has gone viral in India.

Mr Modi's two-day visit - his first to the Kremlin since 2019 - coincides with a Nato summit in Washington, where the 2022 invasion will be a major theme.

India, a key global economy, has close ties with both Russia and the US and its partners and officials in Delhi are playing down questions over the timing of Mr Modi's trip. They say the annual summit is part of a long-standing strategic partnership and its scheduling has nothing to do with the Nato summit.

But a sour note has been struck with the US expressing concern. State Department spokesman Matthew Miller urged Mr Modi to emphasise Ukraine's territorial integrity during his talks in Moscow.

Mr Miller also said the US had raised concerns with India regarding its relationship with Russia.

"We would urge India, as we do any country when it engages with Russia, to make clear that any resolution to the conflict in Ukraine needs to be one that respects the UN charter, that respects Ukraine's territorial integrity, Ukraine's sovereignty," he said at a press briefing on Monday.

Ukraine's President Volodymyr Zelensky went further - and did not mince his words.

"It is a huge disappointment and a devastating blow to peace efforts to see the leader of the world's largest democracy hug the world's most bloody criminal in Moscow on such a day," he posted on X (formerly Twitter) late on Monday.

The Nato summit in Washington, which begins on Tuesday, is being held to mark the 75th anniversary of the Western defence grouping which was mainly formed as a bulwark against the then Soviet Union after World War Two.

Nato countries have been vehemently opposed to Moscow’s invasion of Ukraine, while India and Mr Modi have refrained from any explicit criticism of President Putin except calling for dialogue and diplomacy to resolve the conflict.

As Western nations try to isolate Moscow by imposing sanctions, President Putin has been having summit-level meetings with leaders of key nations like China, India, Turkey and others.

Some are now asking whether Mr Modi's presence in Moscow could be to Mr Putin's advantage. Is the message India is sending out playing into the hands of Russia?

“The bilateral visit this time is just a scheduling priority that we have undertaken. And that’s what it is,” Vinay Kwatra, permanent secretary to the Indian foreign ministry, told the BBC ahead of Mr Modi’s visit, rejecting any connection between the two events.

India and Russia share close defence and strategic relations from Cold War days and Moscow remains a key supplier of weapons. India, which maintains one of the largest militaries in the world, has long-standing border disputes with its neighbours Pakistan and China.

Experts say Mr Modi giving importance to Moscow is not a surprise and the relationship goes beyond defence procurement.

“If you look at the historical trend, it [Moscow] has been one of the constants in Indian foreign policy,” Pankaj Saran, former Indian ambassador to Moscow, told the BBC.

“The main pillars of the relationship include defence co-operation, energy and science technology.”

Over the years, Russia has provided technical assistance to build several nuclear power plants in India.

Since the Ukraine war began, Delhi has also been buying billions of dollars of discounted oil from Moscow after Western nations imposed sanctions on Russia to limit what it could sell or charge for the product.

Driven by a surge in the purchase of oil, bilateral trade between India and Russia in the last few years has soared to $65bn (£50.76bn). India’s exports to Russia stand at just $4bn.

Indian officials say a key priority for Mr Modi will be to address this trade imbalance and encourage Russian investment in India as well as moving some defence production to India.

For the past 20 years, the West, particularly the US, has cultivated closer ties with India in what many see as a bulwark against the threat posed by an increasingly assertive China.

India also became a member of the Quad - a strategic forum with the US, Australia and Japan - which is seen as a grouping aimed at countering Chinese influence in the Asia Pacific.

But faced with increasing Western hostility, President Putin has developed closer strategic and economic ties with Beijing. The development has not gone unnoticed in India, China's long-time rival.

A deadly brawl on the disputed border in Ladakh region in June 2020 killed 20 Indian and at least four Chinese soldiers and escalated tensions.

There are apprehensions in India that it may be left out of the Moscow-Beijing equation.

“One option currently being exercised by Delhi is to keep the Russia channel open to maintain the friendship and avoid taking any measures which may further aggravate Russia’s drift into Chinese arms that is being caused by US and Western policies,” says Mr Saran.

Though Delhi has diversified its weapons inventory in recent decades by buying American, French and Israeli arms systems, it still relies heavily on Moscow and there have been concerns the war in Ukraine has had an impact on its defence exports.

“There are reports of delays in the supplies of some spare parts and the delivery of the remaining S-400 anti-missile defence system. So, there will definitely be some discussion on this during the visit,” says Anil Trigunayat, a former ambassador and now a Distinguished Fellow at the Vivekananda International Foundation in Delhi.

Delhi and Moscow are not without their own differences. There have been several reported cases of Indian nationals who were lured with false promises of lucrative job offers and ended up fighting for the Russian army in Ukraine. Four Indians have died so far in the fighting.

Indian officials insist that during this visit, Mr Modi will press his Russian counterparts for an early discharge of Indians - thought to number in the dozens - still fighting in the war.

India is aware that it needs both the United States and Russia to counter its rival China. Hence, it feels the need to strike a balance not to offend either of the two.

“India follows a policy of strategic autonomy and multi-alignments. We have strategic relationships with both the US and Russia. These are mutually exclusive partnerships,” says Mr Trigunayat.