Japan and Russia on Wednesday signed a deal that will see them jointly explore and develop a potentially lucrative oil and gas field off Russia's Far East coast.
Japanese firm Inpex and Russia's Rosneft state oil giant agreed to work together on the reserve, estimated to hold around 3.4 billion barrels of oil, according to the Yomiuri Shimbun, off the Russian state of Magadan.
That reserve equates to around three years' worth of oil imports for resource-strapped Japan.
Under the agreement, the companies will establish joint ventures to carry out the exploration, with Inpex holding a third of each, a release from the Japanese company said.
"Inpex is pleased to announce that it has signed the cooperation agreement with Rosneft... to pursue the opportunity to jointly explore and develop exploration blocks, Magadan 2 and 3, in the Sea of Okhotsk" the statement said.
"It is expected that the partnership with Rosneft could be developed through this particular project and enable Inpex to have an opportunity to expand its activities in Russia, a country with huge hydrocarbon reserves."
The deal comes after Japanese Prime Minister Shinzo Abe and Russian President Vladimir Putin agreed to cooperate on projects in Russia's Far East when Abe visited Moscow last month.
Also last month, Rosneft and Japan's Marubeni Corporation signed a deal on the possible construction of a liquefied natural gas (LNG) plant in the Russian Far East.
The Japanese government will back the plan, with its Japan Oil, Gas, and Metals National Corp. (JOGMEC) financing 50-75 percent of exploration costs, the Yomiuri said.
Exploration work will start as early as 2017 and development will begin sometime in the 2020s, it said.
Tokyo is eager to tap Russia's vast natural resources because of Japan's own minimal energy supplies.
The world's third-largest economy is already cooperating with Russia in natural gas production in various Sakhalin Island projects.
Analysts say despite historical animosities that include a decades-long territorial row that has prevented the two sides from signing a World War II peace treaty, Tokyo and Moscow are groping for a closer partnership, in a region eyeing China's might with growing unease.
Public nervousness over nuclear power in the aftermath of the tsunami-sparked disaster at Fukushima has pushed Japan back to a greater reliance on fossil fuels.