TOKYO -- Seven decades after agreeing to restore diplomatic ties, Russia and Japan now share only a tenuous relationship, built largely on a shared interest in trade in energy.

"We once again urge the Tokyo authorities to reconsider and change their approach by abandoning their hostile steps toward Moscow, Russian Foreign Ministry spokeswoman Maria Zakharova wrote on Oct. 13. Her statement came just three hours after news emerged that Russia's Federal Security Service had detained a reporter from Japan's Hokkaido Shimbun.

This followed the Japanese government's Oct. 2 decision to impose additional sanctions on Russia over its war in Ukraine. Tokyo banned the provision of services to 35 vessels in the "shadow fleet" that transports Russian oil, a key source of revenue for Moscow.

That measure, in turn, was in effect a response to Russian President Vladimir Putin's August visit to the southern Kuril Islands which Russia controls and Japan claims as the Northern Territories.

The protracted war in Ukraine has exhausted Russia's economy. As costs have ballooned, the government has been forced to increase its budget deficit forecast to 3.2% of gross domestic product from 1.6%. The draft budget for 2027 includes 17.1 trillion rubles ($207 billion) in military spending -- the most of any year going back to the 2022 invasion.

Faced with this challenge, Russia looks to sway Japan with a combination of pressure and enticement.

At an international forum in Moscow on Oct. 1, Putin said that "we are interested in cooperation with Japan" and that Russia will support Japanese companies that "continue to cooperate with the Russian Federation." The goal is to take advantage of Tokyo's own predicament. The closing of the Strait of Hormuz has forced Japan to move away from relying on the Middle East for energy. It would be difficult for the country -- which imports nearly all of its fossil fuels -- to cut off supply from Russia, only a short distance away by sea.

Russia was Japan's third-largest source of liquefied natural gas imports in 2025, accounting for 8.9% of the total. Japanese companies have maintained stakes in the Sakhalin-2 oil and gas project in the Russian Far East even after the invasion of Ukraine. Taiyo Oil bought crude from Sakhalin-2 this past May.

That month, senior officials from Japan's economy and foreign ministries visited Moscow with a delegation of executives at trading houses and other companies. They asked the Russian government to protect the assets of Japanese businesses remaining in the country.

There are concerns that if Japanese players relinquish their interests in Sakhalin-2, they could be scooped up by China, according to a senior official at Japan's Foreign Ministry.

Russia hopes to shore up its economy by using energy as leverage to get Japan to relax its sanctions. Japanese Prime Minister Sanae Takaichi has said she will "comprehensively consider our national interests" when conducting diplomacy with Moscow.

Some argue that Tokyo lacks a long-term perspective on the relationship, putting it in a passive position.

Japan faces the question of how it should deal with Russia as the invasion of Ukraine has left diplomacy at an effective standstill. Foreign policy expert Michito Tsuruoka, a professor on Keio University's Faculty of Policy Management, acknowledges the need for communication while stressing the importance of diplomatic autonomy.

Further diversifying the country's energy supply will be key, and stepping up cooperation with Europe is an option. Japan "needs to take a perspective of giving itself an edge in the Japan-Russia power balance, through such moves as tightening sanctions," Tsuruoka said.