NEMURO, Japan — Tensions between Japan and Russia have intensified following Russian President Vladimir V. Putin’s recent visit to a disputed island chain claimed by both countries, highlighting the enduring conflict over the territory and its impact on the local community.

Mr. Putin’s visit last month to the islands—known in Japan as the Northern Territories and in Russia as the southern Kuril Islands—marked his first in more than 25 years of leadership. The move came amid heightened military activity by Russia near Nemuro, a northern fishing town on Japan’s Hokkaido island located just a few miles from the disputed archipelago. The president toured a seafood-processing plant and was greeted by crowds, as Russian state media showcased the trip as a display of national strength.

The islands have been under Russian control since the closing days of World War II in 1945. Japan has long demanded the return of at least two of the four inhabited islands but Moscow has maintained its sovereignty. No peace treaty formally ending the war has been signed between the two nations. Analysts interpret Mr. Putin’s recent visit as both a strategic move to pressure Japan’s hawkish Prime Minister Sanae Takaichi and a means to galvanize nationalist sentiment within Russia.

Prime Minister Takaichi condemned the visit as "absolutely unacceptable," stating it wounded the feelings of the Japanese people and protesting Russia’s portrayal of the islands on new world maps. Nonetheless, Japan has not imposed new penalties in response, balancing its diplomatic stance against ongoing concerns over energy imports from Russia, including about 10 percent of its liquified natural gas supply.

Nemuro, a town of roughly 22,000 residents known for fishing and chilly winters, sits at the intersection of these geopolitical currents. For decades, Nemuro has been a center of Japan’s campaign to assert sovereignty over the islands, with museums, billboards, and monuments dedicated to the cause. Yet the town also depends heavily on trade and fishing rights with Russia, making any diplomatic strain acutely felt in its local economy.

Mayor Masatoshi Ishigaki expressed concern over the consequences of escalating tensions for livelihood and commerce, noting that Russian-imposed restrictions have already curtailed fishing of salmon and trout, and reduced trade with Russian counterparts. Once a bustling hub for Russian sailors and tourists, Nemuro has seen a marked decline in Russian visitors following the deterioration in bilateral relations. Local shops and schools that once catered to Russians now confront dwindling activity.

The demographic decline of Nemuro mirrors that of many rural Japanese towns, with its population shrinking from about 50,000 in the 1960s to less than half that today. Younger residents show less engagement with the territorial dispute compared to the older generation. Some, like activist Taiko Kodama, who was born in the disputed islands and expelled in 1947, continue to observe annual ceremonies mourning those lost and emphasizing the belief that the islands were taken unjustly.

Former island resident Hiroshi Tokunou, aged 92, advised a balanced approach, highlighting the need for Japan to maintain firmness while leaving open the possibility of improved future relations. Still, he worries the issue may lose prominence as generational shifts bring differing perspectives.

Meanwhile, Russia has intensified its military presence near the islands, framing its claims as grounded in “international documents,” while criticizing Japan’s sanctions imposed after Russia’s 2022 invasion of Ukraine. Russia has also taken symbolic measures, including erecting a statue depicting the Soviet soldier destroying Japan’s imperial chrysanthemum seal, deepening the symbolic divide.

With no resolution in sight, the decades-old dispute continues to affect diplomatic relations and the everyday lives of those in Nemuro, caught between national loyalty, economic realities, and shifting geopolitical forces.