MOSCOW (AP) — Russian President Vladimir Putin has signed a bill to withdraw from an international treaty allowing surveillance flights over military facilities, following the U.S. exit from the pact. The bill was endorsed by Russian lawmakers after U.S. officials told Moscow last month that President Joe Biden’s administration had decided not to reenter the Open Skies Treaty that the U.S. left under President Donald Trump. Putin’s signature on Monday starts a six-month countdown for the Russian exit to take effect. The Open Skies Treaty was intended to build trust between Russia and the West by allowing the accord’s more than three dozen signatories to carry out surveillance flights over each other’s territories to oversee troop deployments and other military activities.