US President Joe Biden has warned Russia against using nuclear weapons in its war on Ukraine. “They’ll become even more of a pariah in the world than they ever have been,” Biden told US broadcaster CBS. Asked how the US government would react in such a case, Biden said, “You think I would tell you if I knew exactly what it would be? Of course I’m not going to tell you.” However, he made it clear that there would be serious consequences, saying it would “change the face of war, not like anything since World War II.” The full interview is due to be broadcast on Sunday.