The present research addresses the impacts of the instrumentalization of the internet by the Islamic State (IS) on the security and defense doctrine of the United Kingdom, particularly subsequent to the attacks that the group influenced/led on British territory in the first half of 2017. This instrumentalization is presented in a multidimensional way, however, this paper delves into the distribution of propaganda, the recruitment of followers and the provision of information on how to carry out an attack. Being the 2017 attacks a neural point in British history, an analysis is presented on the changes in discourse and action that occurred in the United Kingdom after the events with respect to the internet as a tool of outlawed groups. The research then seeks to relate the 2017 terrorist attacks to an unprecedented increase in the regulation of the internet in the UK. This work was a thesis for the 2018 undergraduate degree in International Relations at Pontificia Universidad Javeriana.