The invention relates to an environment monitoring system (3) for a vehicle (1), wherein the environment monitoring system (3) comprises: at least two distance sensors (4-1, 4-2, 4-3) for detecting distance by measuring the propagation time of detection signals, wherein the distance sensors (4-1, 4-2, 4-3) are each designed as a transmitting unit and receiving unit for the detection signal and, in a direct operating mode, emit detection signals, receive reflected components of the detection signals emitted by the distance sensors; and emit active measurement signals according thereto; and a control device (5), which receives the measurement signals of the distance sensors (4-1, 4-2, 4-3) and determines an object distance (s) of detected objects (10). According to the invention, at least one distance sensor (4-1, 4-2, 4-3) additionally can be operated in an indirect operating mode in order to detect a detection signal emitted by another distance sensor (4-2, 4-3, 4-1) and reflected by the object (10) and in order to generate an indirect measurement signal.