Multimodal, low intensity, kinetic as well as non-kinetic threats to international peace and security including cyber war, low intensity asymmetric conflict scenarios, global terrorism, piracy, transnational organized crime, demographic challenges, resources security, retrenchment from globalization and the proliferation of weapons of mass destruction were identified by NATO as so called "Hybrid Threats" (cf BI-SC Input for a New NATO Capstone Concept for The Military Contribution to Countering Hybrid Enclosure 1 to 1500/CPPCAM/FCR/10-270038 and 5000 FXX/0100/TT-0651/SER: NU0040, dated 25 August 2010). This submission aims to introduce the audience to this form of security threat with a particular focus on "cyber" terrorism and war. This new form of conflict in the fifth dimension has a truly hybrid risk potential and warrants a new holistic counter approach: from law enforcement, counter cyber strategies to kinetic responses. The authors will present the findings of an ongoing Hybrid Threat experiment, which is being undertaken at the Swedish Defence College, with a focus on the role of cyber attacks within the wider context of asymmetric conflict and how the existing legal framework governing the use of force and the law applicable to hostilities does not necessarily reflect on this new form of threat.