Despite the Taiwanese government's unsuccessful attempts in cracking down on the fourth channels, including a major raid in which 370000 kilograms of coaxial cables were forcibly removed and destroyed over a four-month period in 1991, the straw that broke the camel's back only occurred when the United States began threatening trade sanctions against Taiwan in retaliation for massive copyright infringement committed by the fourth channels, in part due to the fourth channels' illegal retransmission of satellite signals from domestic and foreign sources, especially those from Hong Kong, Japan and the United States which became possible only when satellite receptions became legal as explained above.