My dog is suddenly attacking the other dogs for food?

My jack russll has always been sweet and playful he has never been aggressive except to people that present a threat. however lately he has been attacking my chipoodle and Chihuahua over food they have eaten with each other since they were puppies so I’m trying to understand his new found aggression over food. he was fixed about three years ago I don’t know if that’s a factor since all the dogs have been fixed. they eat regularly so i know that he’s not doing it because he’s starving now I have to separate them he is becoming a danger to the other dogs but he has never attacked the people he knows that get near him