value of the U.S. dollar. March 11: OPEC threatens "appropriate sanctions" against companies that "fail to comply with ... any action taken by a Member Country in accordance with [OPEC] decisions." June 1: Iraq nationalizes Iraq Petroleum Company's (IPC) concession owned by British Petroleum, Royal Dutch Shell, Compagnie Francaise des Petroles, Mobil and Standard Oil of New Jersey (now Exxon). The concessions were valued at over one billion dollars. June 9: In a show of support for Iraq, OPEC moves to prevent companies whose interests were nationalized in Iraq from increasing production elsewhere; appoints mediators between Iraq and IPC. September 30: Libya acquires a 50 percent interest in two ENI concessions. October 27: OPEC approves plan providing for 25 percent government ownership of all Western oil interests operating within Kuwait, Qatar, Abu Dhabi and Saudi Arabia beginning on January 1, 1973, and rising to 51 percent by January 1, 1983. (Iraq declines to agree.) Agreements signed on December 21. 1973 January 11: U.S. Phase III price controls begin. Allows for voluntary instead of mandatory price control on all U.S. prices. This does not prevent a sharp rise in heating oil prices caused by a severe winter and shortage of product. January 17: U.S. President Richard Nixon suspends mandatory oil import quota on No. 2 heating oil through April 30. January 23: Shah of Iran announces that the 1954 operating agreement between a consortium of oil companies and Iran will not be renewed when it expires in 1979. The consortium was formed in 1954 as a means to settle a dispute between a new ministry in Iran and the Anglo-Iranian Oil Company (AIOC). The consortium included Standard Oil of New Jersey, Standard Oil of California, SOCONY-Vacuum, the Texas Company, Gulf, Royal Dutch-Shell, the Compagnie Francaise de Petroles, and the AIOC. February 28: Iraq and IPC reach an agreement on compensation for nationalization. March :Special Rule No. 1 reimposes mandatory (Phase II) price controls on the 23 largest oil companies. Smaller companies, representing 5 percent of the market, enjoy uncontrolled prices. March 16: Shah of Iran and Consortium members agree to nationalize all assets immediately in return for an assured 20-year supply of Iranian oil. March 16: OPEC discusses raising prices to offset decline of U.S. dollar value. April 1: OPEC increases posted prices by 5.7 percent. April 18: U.S. Government ends Mandatory Oil Import Program. Program, established in 1959 by President