Political problems cannot be ignored. Heavy
 investments have been made by United States companies
 in foreign ore deposits. Some of these are in
 strategically sensitive areas. Even if not involving
 U.S. capital, traditional foreign sources of iron
 ore, or newer and better sources, must be available
 in large measure to supply domestic needs until
 such time as technology permits the competitive
 processing of domestic low-grade deposits.


 Many large domestic copper producers, through
 subsidiaries or stock holdings, operate foreign
 copper-producing properties in Canada, Mexico,
 Chile, Peru, the Republic of South Africa, and
 Zambia. .

 Nationalization of U.S. interests in Chile was begun
 in April 1967 .

 In August 1969 the Zambian government announced that
 it would assume 51 percent control of the Zambian
 copper industry.(40)

 As the data of Table 2 indicate, the United

States still owns within its borders a substantial share

of total world reserves of iron and copper ores. But

demand for ores within the United States and the rest

of the world have made those deposits look small, and

even with the use of foreign ores, costs are expected

to rise in the future, more so for copper than for

iron.

 40
 U.S. Department of the Interior, Bureau of
Mines, Mineral Facts and Problems, 1970, Bureau of
Mines Bulletin No. 650 (Washington, D. C.: Government
Printing Office, 1970), p. 313; p. 537.