Very interesting article. And it's telling why Johnson didn't reveal what Nixon was doing.

He orders the Nixon campaign to be placed under FBI surveillance and demands to know if Nixon is personally involved.

When he became convinced it was being orchestrated by the Republican candidate, the president called Senator Everett Dirksen, the Republican leader in the Senate to get a message to Nixon.

The president knew what was going on, Nixon should back off and the subterfuge amounted to treason.

Publicly Nixon was suggesting he had no idea why the South Vietnamese withdrew from the talks. He even offered to travel to Saigon to get them back to the negotiating table.

Johnson felt it was the ultimate expression of political hypocrisy but in calls recorded with Clifford they express the fear that going public would require revealing the FBI were bugging the ambassador's phone and the National Security Agency (NSA) was intercepting his communications with Saigon.

So they decided to say nothing.