MOSCOW — Russia on Tuesday test-fired a new intercontinental ballistic missile as part of efforts to modernize the country’s nuclear forces, a launch hailed by President Vladimir Putin just days after his claim that the fighting in Ukraine is nearing an end.Putin said that the nuclear-armed Sarmat missile would enter combat service at the end of the year. It was built to replace the aging Soviet-built Voyevoda.“This is the most powerful missile in the world,” Putin declared, adding that the combined power of the Sarmat’s individually targeted warheads is more than four times higher than that of any Western counterpart....