Russian President Vladimir Putin speaks at a meeting with heads of Russian and foreign news agencies on the sidelines of the 21st St. Petersburg International Economic Forum in St. Petersburg, Russia, June 1, 2017. (Kremlin Photo)

ST. PETERSBURG, Russia, June 1 (Xinhua) -- Russian President Vladimir Putin said Thursday that his country is considering countermeasures against U.S. military threats to its Far Eastern territories, including the disputed islands with Japan.

The United States has deployed missile defense systems in Alaska and now in South Korea, and Russia will not stand by without taking action, Putin said at a meeting with heads of Russian and foreign news agencies on the sideline of the annual St. Petersburg International Economic Forum.

"The U.S. missile defense systems destroy the strategic balance in the world ... we are thinking about how to counter these challenges," he said.

Putin added that in his view, even if Pyongyang drops its nuclear and missile programs someday, Washington will still continue to deploy missile shields in the region under certain pretexts.

Therefore, Russia's military buildup in the Far East, particularly on the four disputed Pacific islands off Japan's northern prefecture of Hokkaido, is a forced response, Putin said.

The island group, called the Northern Territories in Japan and the Southern Kurils in Russia, is quite a convenient location for Russia to carry out a military deployment against the U.S. threats, he noted.

"If we assume that the four islands fall under the sovereignty of Japan one day, theoretically the United States could send troops there," said the Russian president.

"We need to think about lowering the tensions in the region in general. And only then will we be able to reach serious long-term agreements," he said.