India and Japan entered a landmark civil nuclear energy pact after six years.
The deal would allow Japan to export nuclear power equipment and technology to India.
The pact was concluded after five years of discussions in 2015 during Abe's India visit.
Indo-Japan civil nuclear deal
Landmark deal for a cleaner, greener world
External Affairs Ministry Spokesperson Vikas Swarup tweeted, "A landmark deal for a cleaner, greener world! PM @narendramodi and PM @AbeShinzo witness exchange of the landmark Civil Nuclear Agreement."
India's civil nuclear cooperation with the US
The pact is the first Japan has signed with a country that isn't a Non-Proliferation Treaty (NPT) signatory.
The deal would accelerate India's civil nuclear cooperation with the US; US-based Westinghouse is a wholly-owned subsidiary of Japan's Toshiba.
Japan is the only nation to have come under a nuclear attack and was wary of signing an agreement with a non-NPT country - India.
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Japan is the only country to suffer atomic bombings in World War-II; there was political resistance to a nuclear deal with India. Other countries that have signed civil nuclear deals with India include Russia, US, South Korea, France, Mongolia, Argentina, Namibia, Canada, Australia, and Kazakhstan.
Deal expected to boost bilateral economic and security ties
The deal was signed after talks between PM Narendra Modi and PM Shinzo Abe.
Though both the nations had reached an agreement for cooperation in the civil nuclear energy sector in 2015, there were some issues that had to be worked out.
It is expected the deal would boost bilateral economic and security relations and facilitate US-based firms to establish atomic plants in India.
Japanese firms are reportedly the world leaders in nuclear technology and are also nuclear power plant equipment manufacturers; except Russia, most countries in the world are dependent on the Japanese companies.
Japan, a major nuclear energy market player
Japan is a major nuclear energy market player and has a near monopoly over manufacturing reactor vessel with Japan Steel Works (JSW) leading the others; JSW accounts for more than 75% of the business, globally.
Westinghouse is Japan's Toshiba-subsidiary; Hitachi built a General Electric reactor core.
A deal with Japan would help the process of signing nuclear cooperation pacts with other nations for India.
Japanese pact to help India reinforce non-proliferation credentials
The deal would help India advance the technology cooperation with Japan; the country has the upper hand in nuclear fuel fabrication and breeder technology.
The pact would also help India reinforce its non-proliferation credentials.
Japan approving of India's credentials would reportedly be a "shot in the arm" for India as it is trying to enter the Nuclear Suppliers Group (NSG).
14 Nov 2016
Indo-Japan N-deal termination clause is non-binding
The Indo-Japan civil nuclear agreement contains a termination clause, which has specific conditions cited by Japan for terminating the agreement.
The government has insisted that these clauses are non-binding; the Centre clarified that India has made "no additional commitments" on the agreement and "there is no change from the US template."
India and Japan have had several disagreements over nuclear co-operation.