united states foreign policy changed in the 1970s when the united states left vietnam and richard nixon left office due to a political scandal called watergate. in the 1970s and 1980s, the united states had a policy of "detente" with the soviet union. this meant that the two countries signed treaties to stop use of weapons. under nixon and reagan, the united states sent troops and money to many latin american governments to stop them from being communist. this led to violence in latin america. around this time, the economy suffered because the united states was not making as many things as it used to, and because some countries in the middle east were not giving the u.s. as much oil as it wanted (this was called an "oil embargo"). the middle east became very important in american foreign policy after several americans were kidnapped in iran in 1979. in the 1980s, people in the u.s. government sold weapons to people in iran and gave the money to "contra" soldiers in nicaragua. this was called the "iran-contra affair". in the 1970s and 1980s, the u.s. normalized relations with china. the cold war came to an end as communist governments in the soviet union and other countries fell apart.