Putin signed the measure on Saturday, the Kremlin said, three days after it sailed through the Russian parliament with only one vote against. It must be approved by the country's constitutional Court and in a referendum set for April 22.

Russian state television has listed U.S. military facilities that Moscow would target in the event of a nuclear strike, and said that a hypersonic missile Russia is developing would be able to hit them in less than five minutes.

Russian opposition leader Alexei Navalny was detained on Monday over allegations of staging illegal protests, his associates said