Moscow saw no light in the end of the tunnel regarding Russia-U.S. disputes over missile defense issues, Kremlin Chief of Staff Sergei Ivanov said Tuesday. "There is actually a difficult problem of missile technology proliferation. This happens along our, not the U.S., borders," Ivanov told Moscow's KP daily. He said Moscow and Washington "objectively" took different approaches to the security issues because the two countries exist in different geopolitical environment. "Configuration of the world powers and global security are changing. We have to take it into account," the official said, adding that Russia was undertaking all necessary measures to protect itself from new challenges. Among such measures is modernization of the strategic nuclear ground- and sea-based missiles Bulava, Yars, Topol-M, Iskander and prospective frontline aircraft system, Ivanov said. Russia would develop weapons in the coming 30 to 40 years rather than reduce them as the United States had proposed, the official said.