Abstract: The present invention is a system for providing Multiple Independent Levels of Security (MILS) partitioning. The system includes a memory, a bus controller communicatively coupled to the memory via a memory bus, and a MILS controller communicatively coupled to the bus controller via a host-side bus, the MILS controller configured for monitoring and controlling system transactions. The system further includes a plurality of input/output (I/O) devices communicatively coupled to the MILS controller via a plurality of corresponding device-side buses. The system further includes a MILS separation kernel configured for mapping regions of the memory to a plurality of user partitions. Each I/O device included in the plurality of I/O devices is allocated to a partition included in the plurality of partitions and is isolated from MILS separation kernel space. The MILS separation kernel is configured for guaranteeing isolation of the partitions of the memory.