Watergate prosecutors had evidence that operatives for then-President Richard Nixon planned an assault on anti-war demonstrators in 1972, including potentially physically attacking Vietnam whistleblower Daniel Ellsberg, according to a never-before-published memo obtained by NBC News.

The document, an 18-page 1973 investigative memorandum from the Watergate Special Prosecution Force, sheds new light on how prosecutors were investigating attempts at domestic political violence by Nixon aides, an extremely serious charge…

In his memoirs, Ellsberg wrote that in May 1972, the White House had flown “Cuban-American CIA ‘assets’ from Miami to Washington to disrupt a rally that I and others were addressing on the steps of the Capitol,” with orders “to incapacitate [me] totally.”