Abstract: An electronic switch for triggering firing of munitions, the switch inclug an electrical circuit having a high voltage source, a sealed two electrode gap in communication with the high voltage source, a microgap in series with the sealed gap, an exploding foil initiator in communication with the microgap, and an energy storage capacitor bridging legs of the circuit between the high voltage source and the sealed gap. A trigger circuit is in communication with the high voltage source and a fire pulse generator, and is provided with a lead extending from the trigger circuit to one of said legs of said circuit between said sealed gap and said microgap. The energy storage capacitor is charged by the high voltage source to a voltage V which is substantially across the sealed gap. A pulse from the fire pulse generator activates the trigger circuit to provide a high voltage potential V.sub.t across the sealed gap, such that voltage V+V.sub.t breaks down the sealed gap to permit conduction therethrough.