Putin called the US deployment of an advanced missile defense system in South Korea amid tensions on the Korean Peninsula a "challenge" to Russia, at a meeting with representatives from foreign news agencies in St. Petersburg, according to the Kremlin's announcement.

He blamed the United States for "pushing the arms race into a new round," and noted that Russia is "pondering a response."

The Russian leader described the disputed islands as a "convenient place" to "neutralize possible threats."

Putin expressed his country's concern about the possibility of US forces stationed on the islands if Japan takes control of them.

He stressed that it would be "totally unacceptable" that the United States builds military bases or deploys a missile defense system on the islands.

The islands, located off the northernmost Japan prefecture of Hokkaido, were seized by Soviet troops from Japan in the closing days of World War II. (Jiji Press)