The conferences in SPIE Security + Defence crosses the divide between fundamental optical science and the application of the underpinning technologies in advanced defence and security systems. This is a unique symposium that will offer many opportunities to network with colleagues from a variety of disciplines in academia, industry, and government from all over the world, while addressing the new challenges that continue to emerge: network-enabled capability/network-centric warfare evolve; asymmetric warfare: military operations in the urban theatre; and peace-keeping.