Russia and Argentina have effectively halted cooperation on civil nuclear energy projects, Russia's ambassador to Buenos Aires said, as President Javier Milei's government deepens its alignment with the United States and moves away from previously planned joint ventures with Moscow.

"As far as we know, bilateral cooperation in the peaceful use of nuclear energy is not currently taking place," Ambassador Dmitry Feoktistov told the Russian newspaper Izvestia, adding that joint projects led by Russian state nuclear firm Rosatom, including plans for a nuclear power plant, are not being carried out.

Ties between Moscow and Buenos Aires have cooled since Milei took office in December 2023. The self-described libertarian has pursued closer relations with Washington and has voiced support for Ukraine, a marked shift from the foreign policy of his Peronist predecessors, who held a more neutral stance on the Russia-Ukraine conflict and cultivated economic and energy links with Moscow.

A bilateral agreement on nuclear energy cooperation took effect in 2018, after which the two countries discussed a site for a nuclear power plant that would have included large VVER-1200 reactors as well as land-based and floating facilities, according to Russian broadcaster RTVI. The plans stalled amid Argentina's prolonged economic crisis and have not advanced since.

Since Milei's election, Argentina has joined the United States' FIRST nuclear programme and signed a $1.2bn contract with US company Meitner Energy to build a small ACR-300 reactor. The Argentine government has also announced plans to privatise state nuclear company Nucleoeléctrica Argentina.

The Argentine embassy told Izvestia that Argentina is capable of meeting its nuclear energy needs without foreign assistance, noting that private investment in the sector is governed by versions of the Regime for Incentives for Large-Scale Investments (RIGI), approved by Argentina's Congress.

Russia has also lost its stake in the Tolillar lithium project. Rosatom subsidiary Uranium One had agreed in 2021 to invest $30mn for a 15% stake in the deposit from Canada's Alpha Lithium Corporation, but the Canadian company cancelled the deal in 2022 after sanctions were imposed on Russia following its invasion of Ukraine, according to RTVI. The Tolillar deposit is now being developed by the Italo-Argentine conglomerate Techint.

"Rosatom's subsidiary has focused its efforts on Bolivian projects," Feoktistov said, referring to the company's shift in regional focus following the loss of the Argentine lithium stake.

However, Russia's lithium ambitions in Bolivia have also come under strain as La Paz moves closer to Washington under centrist President Rodrigo Paz, who came to power in November 2025. A decree passed in Bolivia in April 2026 banning direct deals without open tenders has led to a review of existing contracts, leaving the Russian-Bolivian project effectively frozen.

Despite the setbacks, Feoktistov said Russian and Argentine companies retain mutual interest in cooperation in other sectors. "We are recording mutual interest between Russian and Argentine companies in cooperation in areas such as electric power, renewable energy, and the oil and gas industry," he said.

Bilateral trade between Russia and Argentina rose by more than 80% in 2025, driven largely by Russian fertiliser exports, the ambassador said.

Brazil remains Russia's largest partner in Latin America. Russian energy major Rosneft holds stakes in the Solimões oil and gas project in the Amazon Basin, while Rosatom subsidiary INB supplies enriched uranium to Brazil's only nuclear power plant, Angra.

Russia's losses in Argentina and Bolivia echo a broader retreat from Venezuela, once one of the Kremlin's closest allies in Latin America. US forces captured then-president Nicolás Maduro in a raid on Caracas last January, whisking him to New York to face drug-trafficking charges, while Vice President Delcy Rodríguez was sworn in as interim president two days later with US blessing, paving the way for what many see as a Washington-friendly protectorate. Russian Foreign Minister Sergei Lavrov said in February that Russian companies were being "quite openly forced out" of Venezuela under pressure from Washington, even as state oil firm Roszarubezhneft, which took over Rosneft's Venezuelan assets in 2020, insisted it retained ownership of its joint ventures with Venezuela's state oil company PDVSA.