In his first address to officials from the Group of 20 leading economies since his invasion of Ukraine, President Vladimir V. Putin on Wednesday rebuffed criticism that the war’s aggression was “shocking” and accused Western nations of a double standard because of their response to the conflict between Israel and Hamas. Appearing at a virtual meeting of the G20, he called the war in Ukraine “a tragedy” that must be stopped and said Russia had “never refused” to engage in peace negotiations. For Mr. Putin, it was a rare interaction with Western leaders since the start of the war last...