Japan has given in to India’s demand that it be allowed to reprocess spent nuclear fuel from Japanese-made reactors, negotiation sources said, marking a major shift in Japan’s stance against proliferation.

India, a nuclear power that conducted its first weapons test in 1974 using reprocessed plutonium, has not joined the Nuclear Non-Proliferation Treaty. Japan has been seeking measures to guarantee India will not divert extracted plutonium — which could be used to build nuclear weapons — for military use, but no agreement has been reached on the issue, the sources said Thursday.

This is the first time Tokyo has allowed a country using Japanese reactors to conduct fuel reprocessing. Since the Fukushima meltdowns in 2011, Japan has concluded nuclear equipment supply agreements with six countries, including Jordan, Russia, Turkey and Vietnam. But not one had been allowed to reprocess spent fuel generated by the reactors.

As a condition for allowing reprocessing, Japan has suggested throughout the bilateral negotiations, which began in 2010, that India submit an annual report detailing the amount of plutonium generated through reprocessing and where it is stored.

But India rejected the proposal, saying it already has a safeguards agreement with the International Atomic Energy Agency that subjects it to inspection by the nuclear watchdog, the sources said.

Some Japanese officials had been cautious about approving reprocessing, but Tokyo is now set to agree because its ally the United States has already done so, they said.

The U.S. recently reached a broad nuclear agreement with India on condition that India submit certain information regarding extracted plutonium.

Although all of Japan’s commercial reactors remain offline in the wake of the triple meltdown at the Fukushima No. 1 nuclear plant in Fukushima Prefecture, the government has been pushing exports of its nuclear technology.

Sales of nuclear power generation equipment are a key part of Prime Minister Shinzo Abe’s yen-weakening growth strategy to shore up the world’s third-largest economy.