MOSCOW - Indian Prime Minister Narendra Modi met President Vladimir Putin in Moscow on Thursday with the goal of securing what would be his nation's biggest weapons deal with Russia since 2001, strengthening military ties dating back to the Soviet era.

Modi and Putin hailed what they termed a "strategic partnership" at their Kremlin meeting and pledged to boost business ties, with the Indian leader signaling progress on defense projects to ensure his country upgrades its weapons capability.

"As I look to the future, I see Russia as a significant partner in India's economic transformation and in shaping a balanced, inclusive and a multi-polar world," Modi told reporters.

Winning a significant slice of the $150 billion that Modi plans to spend to upgrade his military could be a welcome diversion for Putin, who is bracing for a second year of recession amid Western sanctions and low oil prices. The S-400 air defense missile systems India plans to buy are among the "crown jewels" of Moscow's defense capability, according to Jon Grevatt, Asia-Pacific defense-industry analyst for IHS Jane's.

The Indian prime minister, who arrived in the Russian capital on Wednesday for a private dinner with Putin, presided over the signing of several agreements, including for the manufacture of Russian helicopters in India and joint oil and gas exploration and production in Russia.

Modi also took part in an event at the Kremlin with Russian and Indian CEOs on Thursday.

"Russia and India have a very strong partnership that the U.S. can only aspire to," Grevatt said. "Sales from America may ebb and flow, but the sales from Russia will remain strong because there are so many ongoing programs between the two countries."

Among the agreements on Thursday, state-run OAO Rosneft and India's Oil & Natural Gas Corp. signed a memorandum of understanding on joint exploration and production at oil and gas fields in Russia, including offshore projects. They also agreed that ONGC may increase its stake in the Rosneft subsidiary Vankorneft after already buying 15 percent, and Rosneft and Oil India signed an accord on possible onshore projects in Russia.

OAO Rosatom, the state-run nuclear power operator, agreed on assembling Russia-designed products for nuclear power plants in India, and Modi said Russian helicopters are to be made in India. Russia's Kamov OAO is to name an Indian partner to build 200 Ka-226T light military cargo helicopters in India. The deal may be valued at $1 billion, India TV reported earlier.

India's defense acquisition panel last week approved buying five S-400 systems. While the price is still to be set, sources say it's likely to be about $4.5 billion.