"The proposed acquisitions of major operations in six major U.S. ports by Dubai Ports World and of Unocal by the China National Offshore Oil Corporation (CNOOC) sparked intense concerns among some Members of Congress and the public and has reignited the debate over what role foreign acquisitions play in U.S. national security. The United States actively promotes internationally the national treatment of foreign firms. Some Members of Congress and others are concerned with this policy, however, particularly with how it applies to allowing government owned companies unlimited access to the Nation's industrial base. Much of this debate focuses on the activities of a relatively obscure committee, the Committee on Foreign Investment in the United States (CFIUS) and the Exon-Florio provision, which gives the President broad powers to block certain types of foreign investment."
CRS Report for Congress, RL33312