Around the world, countries are implementing stricter national security-based reviews of cross-border investments. The Committee on Foreign Investment in the United States (CFIUS), often viewed as a model for other countries' regimes, is no exception. Final regulations fully implementing the Foreign Investment Risk Review Modernization Act of 2018 (FIRRMA) recently took effect, dramatically changing CFIUS's impact on cross-border M&A and even non-controlling inbound foreign investment. The panel, comprising representatives of CFIUS agencies as well as foreign investment practitioners, will discuss key elements of the new rules and how they will expand reviews of cross-border investments, shift regulatory risk between the parties to M&A transactions, and affect the certainty and timing of closing.