A safety and arming unit for a fuse includes a firing chain having first and second firing devices defining an intermediate space therebetween and a barrier blocking the intermediate space in a safe position. The firing chain is brought into an armed position by a releasing movement vacating the intermediate space. First and second mutually independent securing devices lock the barrier in the safe position and execute an unlocking action based on two mutually independent physical arming parameters. A compact and very reliable safety and arming unit can be achieved in this way.