Japan's ambassador to Moscow returned home on Wednesday as Tokyo protested against Russian President Dmitry Medvedev's visit to the disputed Kuril isles.
Masaharu Kono arrived at Narita airport on an Aeroflot flight to brief Foreign Minister Seiji Maehara about the visit as well as Russian domestic affairs.
"I received an order to return and discuss the current Russian affairs and the condition of Japan-Russia relations," Kono told reporters at the airport.
The Japanese government of Prime Minister Naoto Kan has been put on the defensive after Medvedev Monday visited the Kuril Islands, which lie north of Japan's Hokkaido island, despite Tokyo's earlier protests.
The islands have been controlled by Moscow since they were seized by Soviet troops at the end of World War II, but Tokyo claims the southernmost four as Japanese territory.
The Russian leader's action came at a sensitive diplomatic moment in Japan, which has also faced a tense territorial dispute with China while attempting to mend soured ties with Washington after a disagreement over a plan to relocate a US airbase in Japan.
Washington has said the Japan-US military alliance applies to the territorial row with China. But the territorial dispute with Russia is not covered, the US State Department said.
Sensitivities are high as Tokyo prepares to host a summit of Asia-Pacific Economic Cooperation forum nations in Yokohama this month.
It was not immediately clear how long Kono will stay in Japan.
Medvedev become the first leader from Russia or the former Soviet Union to travel to any of the disputed islands, triggering an immediate protest from Japan, which condemned it as "very regrettable".
Prime Minister Kan said Tuesday night he ordered Kono to make a "temporary" return home "because I wanted to hear what has happened."