Since the beginning of the Russian operation in Crimea in 2014, which led to an illegal and illegitimate annexation of the peninsula, hybrid warfare became a buzzword used in all transatlantic security policy circles. For many in the West, the Crimea operation came as a surprise and the term “hybrid warfare” was meant to intellectually embrace this shock. Yet, many experts claim that there is nothing new in the current model of hybrid warfare as it is based on hybrid wars conducted in Vietnam, Chechnya, Iraq, Afghanistan, and Lebanon, to name a few. In fact, hybrid warfare can be more easily characterised than defined. But is it really – to use the famous expression by U.S. Secretary of Defense Donald Rumsfeld – a known unknown?