AP —

Russian President Vladimir Putin on Thursday made his first visit to the Kuril Islands, a Moscow-controlled Pacific archipelago that also is claimed by Japan, which voiced a diplomatic protest over the trip.

Putin visited a fish plant, a hospital and a school on Iturup, one of the volcanic chain’s southern islands. He also briefly spoke to local residents and met with the governor of Russia’s Sakhalin region, Valery Limarenko.

Japan asserts territorial rights to the four southernmost islands of the chain, which it calls the Northern Territories. The Soviet Union took them from Japan in the final days of World War II, and the dispute kept the countries from signing a peace treaty formally ending their hostilities.

Decades of diplomatic efforts to negotiate a settlement haven’t produced any visible results. Moscow over the years has also bolstered its military presence on the Kurils in moves that appeared to underscore its firm stance in the dispute.