Russian President Vladimir Putin on Wednesday authorized the state-owned telecoms giant Rostelekom to buy out Finnish mobile operator Nokia’s stake in a Russian joint venture. Under laws introduced in response to Western sanctions, the Kremlin leader must personally approve any deal that involves the exit of a Western company operating in sectors of the economy Moscow considers strategically important. In a decree published Wednesday, Putin authorized a subsidiary of Rostelecom — which the government controls through various state development corporations and a state-owned bank — to buy out No…