The article argues that technological innovations change war, and pushes to innovate, to rethink strategic, operational and tactical decisions which raise new issues of moral and legal impacts. Small states have to redefine their defence concerning major technological trends. Technological progress will only strengthen the polycentric system in military technology because war is waged in six domains; small states do not have access to all of them, and at the same time they lack financial and industrial capabilities. Artificial intelligence, the increasing role of cyber and informational elements, unmanned systems, 3D printing and changing battlefield force to adapt the defence of small states. Small states have to plan their defence in three periods – peace, attack until full occupation and resistance. Technological innovations for the defence of small states are important, but the most crucial element is preparation of military and society for total resistance with the focus on denying victory for the aggressor. Small states cannot compete with technologically advanced powers (in terms of arms quality and quantity), so they have to adapt by expanding their fighting force, adapt to defend in the areas which decrease technological advantage and increase uncertainty. Small states also have to approach defence more creatively by exploiting non-conventional instruments, focusing on capabilities to fight without clear command and control, investing in personal skills of officers and soldiers, as well as maintaining symbiotic relations with technologically superior allies.