to 1951. In the years immediately after World War II, the United States had replaced the United Kingdom as the "paramount" power in Afghanistan's affairs. A 1950 journal by Arnold Fletcher from the University of Southern California noted the state of this country to the United States and described it as: However, Fletcher also noted the difficulties of forming relations, amid tense Afghan-Pakistani border skirmishes: The first American expedition to Afghanistan was led by Louis Dupree, Walter Fairservis, and Henry Hart. In 1953, Richard Nixon who was serving as U.S. Vice President at the time made an official diplomatic visit to Kabul. He also took a short tour around the city and met with local Afghans. In 1958, Prime Minister Daoud Khan became the first Afghan to speak before the United States Congress in Washington, D.C. His presentation focused on a number of issues, but most importantly, underscored the importance of U.S.-Afghan relations. While in the U.S. capital, Daoud met with President Eisenhower, signed an important cultural exchange agreement, and reaffirmed personal relations with then Vice President Richard Nixon that had begun during the latter's trip to Kabul in 1953. The Prime Minister also traveled around the United States visiting the New York Stock Exchange, the Empire State Building, hydroelectric facilities at the Tennessee Valley Authority (TVA), and other sites. At that time the United States declined Afghanistan's request for defense cooperation but extended an economic assistance program focused on the development of Afghanistan's physical infrastructure—roads, dams, and power plants. Later, American aid shifted from infrastructure projects to technical assistance programs to help develop the skills needed to build a modern economy. Contacts between the United States and Afghanistan increased during the 1950s, especially during the Cuban Revolution between 1953 and 1959. While the Soviet Union was supporting Cuba's Fidel Castro, the United States was focusing on Afghanistan for its strategic purposes. This was mainly to counter the spread of communism and the strength of the Soviet Union into South Asia, particularly the Persian Gulf. President Eisenhower made a state visit to Afghanistan in December 1959 to meet with its leaders. He landed at Bagram Airfield and then drove from there to Kabul in a motorcade. He met with King Zahir Shah, Prime Minister Daoud and a number of high-ranking government officials. He also took a tour of Kabul. After this important visit, the United States began to feel that