The 30-year armed conflict between Turkey and the Kurdistan Workers’ Party (PKK) for Kurdish self-determination has had specific effects for the Kurds, including dispossession and forced migration. The Kurdish diaspora across Europe has been subject to sustained security operations in relation to the listing of the PKK as a ‘terrorist organization’. This article draws on qualitative research about the experiences of Kurdish Londoners visited by MI5 in 2010–2011. It identifies the processes and practices that criminalize Kurds as the collective subjects of security policing, or ‘suspect community’. I argue that ‘disruption’ is the key mode of power in UK proscription policy animating processes of criminalization and provides insights for criminological understanding of pre-emptive counter-terrorism. The disruption strategies I evidence in this case study de-stabilize Kurdish ethno-political identifications and political claims. I argue that attention to the disruption of self-determination and diaspora—as both concepts and social practices—elaborates the criminalizing effects of the listing of the PKK.