German Chancellor Olaf Scholz has called on Russia to rule out the use of nuclear weapons in its war against Ukraine. “It is not permitted, it is unjustifiable, to use nuclear weapons in this conflict,” Scholz said at a convention of his Social Democrats party in Berlin on Saturday. “We call on Russia to clearly state that it will not do so. That would be a line that must not be crossed.” Scholz had, together with Chinese President Xi Jinping, warned against nuclear escalation during a visit to Beijing on Friday, calling nuclear threats “irresponsible and incendiary.” Xi meanwhile said the int…