This paper analyses the regulation of foreign direct investment (FDI) in relation to critical infrastructure from a Swiss and European perspective. It examines how growing geopolitical tensions and security concerns have led to increased scrutiny of foreign investments, particularly those involving state-linked investors. After outlining key concepts of FDI, the paper compares the legal frameworks governing FDI screening in Switzerland and the European Union. Special attention is given to Chinese investments in critical infrastructure within the EU, illustrated by a case study of COSCO’s investment in the Port of Hamburg. In addition, the analysis identifies regulatory gaps and outlines recent efforts to strengthen FDI screening mechanisms.