 Complete the following phrase:  Relations were also strained with the United States. In November 1964, Kambona publicly announced the discovery of evidence of a U.S.-Portuguese plot to invade Tanzania. The evidencewhich consisted of three photostat documentswas labelled a forgery by the U.S. Embassy and after Nyerere returned from a week at Lake Manyara he acknowledged that this was a possibility. After the U.S. launched 