The acquisition of Unocal -- which includes Unocal's wholly owned subsidiary, Union Oil Co. of California -- by either Chevron Corporation or the China National Offshore Oil Corp. (CNOOC) could have been subject to review by either of two U.S. agencies; which agency reviews a proposed merger or acquisition depends on the origin of the parties, and the reviews are conducted for different reasons. Certain mergers or acquisitions between domestic entities may be evaluated under the Premerger Notification Act by either the Federal Trade Commission (FTC) or the Antitrust Division of the Department of Justice in order to assess a transaction's likely effect on competition within the United States. If the merger partner or acquiring party is a non-U.S. entity, the Committee on Foreign Investment in the United States (CFIUS) may monitor and evaluate the impact of the proposed transaction and determine whether the acquisition implicates national security issues. If the President determines that national security is threatened by the acquisition, he may suspend or prohibit the acquisition. This report will set out, briefly, the background and conclusion of the competing bids for Unocal, the mechanics of the review processes, and present some Congressional reaction to the situation. On August 2, 2005, CNOOC withdrew its bid for Unocal, and on August 10, 2005, Unocal shareholders approved the acquisition by Chevron. This report will not be further updated.