Foreign Minister Fumio Kishida plans to delay his visit to Russia to September or later out of consideration for Japan's alliance with the United States, a country that has taken a tough stance toward the Kremlin over the crisis in Ukraine, government sources said Wednesday.

Kishida's trip had been expected to pave the way for Russian President Vladimir Putin to visit Japan this fall. But if Kishida delays his visit further, it may affect Putin's trip to Japan, an event it sees as important in promoting negotiations for territorial disputes involving four Russian-held islands off Hokkaido.

Kishida may be forced to delay his visit again if the situation in Ukraine fails to de-escalate, sources said.

In the wake of Russia's annexation of Crimea in March, Kishida postponed a visit to Russia that had been planned for the following month.

Russia's action has drawn condemnation from major democracies such as the United States, Japan and the European Union. The West also suspects Russia's involvement in the clash between Kiev troops and pro-Moscow rebels in eastern Ukraine.

In a summit earlier this month, the Group of Seven leaders condemned Russia's "illegal" annexation of Crimea and said they "stand ready to intensify targeted sanctions" on Moscow "should events so require."

The G-7 includes Britain, Canada, France, Germany, Italy, Japan and the United States.

Despite coordinated action with the United States and Europe toward the Ukraine crisis, Japan is seeking to maintain a dialogue with Russia in hopes of advancing the territorial issue through a summit between Prime Minister Shinzo Abe and Putin.