<Tr> <Td_colspan="2"> Problems playing this file? See media help . </Td> </Tr> <P> After World War II, U.S. control of the canal and the Canal Zone surrounding it became contentious; relations between Panama and the United States became increasingly tense . Many Panamanians felt that the Canal Zone rightfully belonged to Panama; student protests were met by the fencing - in of the zone and an increased military presence there . Demands for the United States to hand over the canal to Panama increased after the Suez Crisis in 1956, when the United States used financial and diplomatic pressure to force France and the UK to abandon their attempt to retake control of the Suez Canal, previously nationalized by the Nasser regime in Egypt . Unrest culminated in riots on Martyr's Day, January 9, 1964, when about 20 Panamanians and 3--5 U.S. soldiers were killed . </P> <P> A decade later, in 1974, negotiations toward a settlement began and resulted in the Torrijos--Carter Treaties . On September 7, 1977, the treaty was signed by President of the United States Jimmy Carter and Omar Torrijos, de facto leader of Panama . This mobilized the process of granting the Panamanians free control of the canal so long as Panama signed a treaty guaranteeing the permanent neutrality of the canal . The treaty led to full Panamanian control effective at noon on December 31, 1999, and the Panama Canal Authority (ACP) assumed command of the waterway . The Panama Canal remains one of the chief revenue sources for Panama . </P> <P> Before this handover, the government of Panama held an international bid to negotiate a 25 - year contract for operation of the container shipping ports located at the canal's Atlantic and Pacific outlets . The contract was not affiliated with the ACP or Panama Canal operations and was won by the firm Hutchison Whampoa, a Hong Kong--based shipping interest owned by Li Ka - shing . </P>

Who owns the rights to the panama canal