d. Afghanistan.
Before the end of 1979, Carter's problems were compounded when the USSR invaded Afghanistan. Though the Soviet Union insisted that it was simply maintaining its power in the region, Carter worried that the Soviets were advancing toward Iran in an attempt to control the world's oil supplies. The United States suddenly found itself back in the Cold War, but with neither the diplomatic leverage to influence Soviet behavior nor the willingness to risk a showdown. Carter responded by announcing a boycott of the 1980 Moscow Olympics, suspending arms limitation talks, raising military spending, and funding Islamic revolutionary forces in Afghanistan.