Against a backdrop of increasingly protectionist political rhetoric, there has been renewed interest in recent years in the ability of governments to intervene in the M&A process to protect national interests. This is a global trend which has now firmly landed in the EU. In September 2017 the European Commission put forward proposals for an EU framework for the screening of foreign direct investments (FDI) on security and public order grounds. A month later, the UK Government published a Green Paper proposing to extend the UK Government's ability to intervene in transactions for national security purposes. In this article, Kyriakos Fountoukakos and Molly Herron consider in detail the EU and UK FDI-screening proposals, and their interaction with the EU and UK merger control regimes.