Members of the Stal youth group picketing the Japanese Embassy with signs reading "The Kurils are our land."
Russia will send new air defense systems, possibly including S-400 rockets, to islands at the center of a territorial dispute with Japan, RIA-Novosti reported Tuesday, citing a General Staff source.
Russia, which occupied the four islands off Japan at the end of World War II, has pressed its claim to the territory with plans to boost investment and its military presence.
"The division will be given a brigade of air defense troops," the news agency quoted the General Staff source as saying.
The air defense systems will consist of short- and long-range weapons, possibly including the Russian S-400 surface-to-air missile defense system, he said.
Interfax quoted a General Staff source as denying the report. A spokesman for the Defense Ministry refused to confirm or deny it.
The Russian-made S-400 can intercept and destroy airborne targets at a distance of up to 400 kilometers, meaning that they could hit aircraft, cruise missiles or ballistic missiles over Japan, RIA-Novosti said.
President Dmitry Medvedev said last week that Moscow would provide the islands with sufficient weaponry to ensure their security as a part of Russia's sovereign territory.
Moscow has an artillery division on one of the islands, but its aging infrastructure is in need of an overhaul.
Medvedev sparked debate over the islands last year when he became the first Russian president to visit the archipelago, known as the southern Kurils in Russia and the Northern Territories in Japan.
Two other senior government officials, including the defense minister, have paid visits to the islands over the past months. Conflicting claims have prevented Moscow and Tokyo from concluding a peace treaty.