Since 1988, the U.S. government has conducted national security reviews of cross-border acquisitions of U.S. businesses through the Committee on Foreign Investment in the U.S. (CFIUS). Historically, CFIUS focused on investments that could result in control of a U.S. business, and the CFIUS process was almost exclusively voluntary – parties sought CFIUS clearance in exchange for a promise the U.S. government would not conduct post-closing reviews of their transactions. A number of important reforms were introduced, however, by the August 2018 enactment of the Foreign Investment Risk Review Modernization Act of 2018 and its implementing regulations. Those include the scope of transactions and technologies falling under CFIUS jurisdiction; the filing process and fees associated with CFIUS reviews; and the range of exemptions from CFIUS jurisdiction that exist. In a guest article, Jonathan Gafni, senior counsel at Linklaters and former deputy national intelligence officer for CFIUS support at the Office of the Director of National Intelligence, outlines the recent CFIUS reforms, with a particular focus on their implications for PE funds during the fund formation process, when investing in portfolio businesses with U.S. operations and when divesting interests in those businesses. See our two-part series on CFIUS: “Understanding the CFIUS Review Process and How to Structure Investments to Minimize Regulatory Risk” (Apr. 2, 2019); and “FIRRMA Expands the Scope of Transactions Subject to CFIUS and Lengthens the Target Acquisition Timeline” (Apr. 9, 2019).