In 1964, NBC televised the 1964 Summer Olympics in Tokyo; in 1972, NBC televised the 1972 Winter Olympics for the first time. 1980 would prove to be a stinging disappointment for the network; after contentious negotiations, NBC won the broadcast rights to the 1980 Summer Olympics. After the Soviet Union invaded Afghanistan, the United States and 64 other countries boycotted the event. NBC substantially scaled back its coverage and lost heavily in advertising revenue. In 1988, NBC televised the 1988 Summer Olympics in Seoul. Since then, it has branded itself as "America's Olympic Network", televising every Summer Olympic Games since the Seoul event, as well as every Winter Olympic Games since 2002 Winter Olympics. In total, NBC has aired 13 Summer and Winter Olympics, the most by any one U.S. network. The Olympic Games have also become an integral part of the network, despite some recurring controversy over its method of broadcast delaying events in part to take advantage of a wider national audience in prime time.