Indian PM Narendra Modi and Japan’s Shinzo Abe have agreed at a summit in Tokyo to accelerate talks on a nuclear energy pact.
They also agreed to strengthen security ties and Mr Modi welcomed Japan’s easing of restrictions on exports of defence equipment and technology.
Mr Modi is on his first major foreign visit since winning May’s election.
The trip is being seen as an attempt by the two democracies to balance the rising weight of China across Asia.
Mr Modi arrived in Japan on Saturday and visited the former imperial city of Kyoto over the weekend.
“The two prime ministers reaffirmed the importance of defence relations between Japan and India in their strategic partnership and decided to upgrade and strengthen them,” the leaders said in a joint statement after their summit.
Mr Modi also welcomed Japan’s relaxation of restrictions on transfer of defence equipment and technology.
The two prime ministers “recognised the enormous future potential for transfer and collaborative projects in defence equipment and technology between the two countries”, the statement added.
The two sides said they would speed up talks on nuclear energy co-operation and claimed “significant progress” although they failed to reach a last-minute agreement on safeguards sought by Japan.
Delhi and Tokyo set a target to double Japan’s direct investment in India in five years from some $2bn (£1.2bn) last year.