One way they do this is through the cease-and-desist letter or e-mail messageor "nastygram."
"A "nastygram." is typically just a signal that the trademark holder wants you to stop using his trademark," says Stuart Mayer, a partner at Mayer Fortkort & Williams, an intellectual-property law firm.
Reid Goldsborough, "Dealing with Internet 'Nastygrams'," Consumers' Research Magazine, April 1, 2003
It is a teletype system, with terminals in the office of the chairman of the Communist Party in Moscow and dual terminals in the Pentagon war room and the White House in Washington. It has been used in occasional international crises, including the Yom Kippur War in 1973. Military officers call the messages "nastygrams."
Bill Prochnau, "The Third World War, and a Trip Through the Looking Glass," The Washington Post, April 30, 1982