NSA historical note
From Dick Morris' book Power Plays:
"In the spring of 1967 [presidential candidate] Nixon asked her [Anna Chennault, widow of General Chennault] to be his advisor on Southeast Asian affairs. As Herbert Parmet writes, 'cables intercepted by the National Security Agency from the South Vietnamese ambassador in Washington revealed that the 'Nixon entourage', working through Anna Chennault, was pressuring [South Vietnamese President] Thieu to resist the peace talks....'
Realizing what Nixon was up to, President Johnson ordered a wiretap on Chennault's phone. Yet whatever evidence the tap turned up went unreleased, since it would put the Democrats in an embarrassing position to admit that they had been using wiretaps to defeat Nixon."