有人提出美军镇压学生的例子，欲为六四的恶行做旁证。这有连接。

http://en.wikipedia.org/wiki/Kent_State_shootings

The Kent State shootings—also known as the May 4 massacre or the Kent State massacre[2][3][4]—occurred at Kent State University in the U.S. city of Kent, Ohio, and involved the shooting of unarmed college students by the Ohio National Guard on Monday, May 4, 1970. The guardsmen fired 67 rounds over a period of 13 seconds, killing four students and wounding nine others, one of whom suffered permanent paralysis.[5]
Some of the students who were shot had been protesting against the American invasion of Cambodia, which President Richard Nixon announced in a television address on April 30. Other students who were shot had been walking nearby or observing the protest from a distance.[6][7]

Photographs of the dead and wounded at Kent State that were distributed in newspapers and periodicals worldwide amplified sentiment against the United States' invasion of Cambodia and the Vietnam War in general. In particular, the camera of Kent State photojournalism student John Filo captured a fourteen-year old runaway, Mary Ann Vecchio, screaming over the body of the dead student, Jeffrey Miller, who had been shot in the mouth. The photograph, which won a Pulitzer Prize, became the most enduring image of the events, and one of the most enduring images of the anti-Vietnam War movement.
The shootings led to protests on college campuses throughout the United States, and a student strike, causing more than 450 campuses across the country to close with both violent and non-violent demonstrations.[8] A common sentiment was expressed by students at New York University with a banner hung out of a window which read "They Can't Kill Us All."[32] On May 8, eleven people were bayonetted at the University of New Mexico by the New Mexico National Guard in a confrontation with student protesters.[33] Also on May 8, an antiwar protest at New York's Federal Hall held at least partly in reaction to the Kent State killings was met with a counter-rally of pro-Nixon construction workers organized by Peter J. Brennan, later appointed U.S. Labor Secretary by President Nixon, resulting in the "Hard Hat Riot".
Just five days after the shootings, 100,000 people demonstrated in Washington, D.C., against the war and the killing of unarmed student protesters. Ray Price, Nixon's chief speechwriter from 1969–1974, recalled the Washington demonstrations saying, "The city was an armed camp. The mobs were smashing windows, slashing tires, dragging parked cars into intersections, even throwing bedsprings off overpasses into the traffic down below. This was the quote, student protest. That's not student protest, that's civil war."[8] Not only was Nixon taken to Camp David for two days for his own protection, but Charles Colson (Counsel to President Nixon from 1969 to 1973) stated that the military was called up to protect the administration from the angry students; he recalled that "The 82nd Airborne was in the basement of the executive office building, so I went down just to talk to some of the guys and walk among them, and they're lying on the floor leaning on their packs and their helmets and their cartridge belts and their rifles cocked and you’re thinking, 'This can't be the United States of America. This is not the greatest free democracy in the world. This is a nation at war with itself.'"[8]
Shortly after the shootings took place, the Urban Institute conducted a national study that concluded the Kent State shooting was the single factor causing the only nationwide student strike in U.S. history; over 4 million students protested and over 900 American colleges and universities closed during the student strikes. The Kent State campus remained closed for six weeks.