The USA did intervene -- it's just that its chief instrument in Rwanda was not the U.N. peace-keepers, but the Rwanda Patriotic Front (RPF): "The present crisis began following the invasion of Rwanda by Tutsi rebel troops from the Ugandan Army under the banner of the Rwanda Patriotic Front (RPF) on October 1, 1990. This well planned invasion was followed by four years of war which ended with the military victory of the RPF in July 1994. The RPF is mainly composed of people from the Tutsi ethnic group who are children or grandchildren of Tutsi exiles who fled into Uganda during Rwanda's 1959 Revolution" (at http://www.udayton.edu/~rwanda/aboutrwanda/history.html). Or Paul Kagame, in particular. The victory of the RPF restored the colonial ethnic hierarchy in Rwanda.
For more, see the following websites:
Fiona Foster, "Massacring the Truth in Rwanda": <http://www.udayton.edu/~rwanda/articles/fiona.html>
"Recent History 1990-1994": <http://www.udayton.edu/~rwanda/aboutrwanda/history.html>.
Adrian Hastings, "Countdown to a Bloodbath": <http://www.udayton.edu/~rwanda/articles/hastings.html>
Harald Marwitz, "Another Side of Rwanda's Blood Bath: Onus May Be Misplaced in Tribal War": <http://www.udayton.edu/~rwanda/articles/harald.html>
Tony Waters, "Conventional Wisdom and Rwanda's Genocide: An Opinion": <http://www.udayton.edu/~rwanda/articles/wisdom.html>
G. Lukongwa Binaisa, Former President of Uganda, "Open Letter to the Youth of Uganda": <http://www.udayton.edu/~rwanda/articles/binaisa.html>
Michel Chossudovsky, "IMF-World Bank Policies and the Rwandan Holocaust": <http://www.udayton.edu/~rwanda/articles/chossudovsky.html>
Barry Crawford, "Rwanda: Myth and Reality": <http://lists.village.virginia.edu/listservs/spoons/marxism-general.ar chive/rwanda>
Barry Crawford, "From Arusha to Goma: How the West Started the War in Rwanda": <http://www.hartford-hwp.com/archives/35/032.html>
"Rwanda -- History": <http://www.sas.upenn.edu/African_Studies/NEH/rw-hist.html>
"Rwanda-Post Colonial History": <http://www.newafrica.com/history/rwanda/post_colonial.htm>
Amnesty International, "Rwanda: Alarming resurgence of killings," 12 August 1996: <http://www.udayton.edu/~rwanda/articles/amnesty.html>
"Rice Caught in Iran-Contra-Style Capers in Africa": <http://www.hartford-hwp.com/archives/30/071.html>
François Ngolet, "African and American Connivance in Congo-Zaire," _Africa Today_ 47.1 (2000) 65-85: <http://calliope.jhu.edu/journals/africa_today/v047/47.1ngolet.html>
Therese LeClerc, "New Evidence on the Role of the US and France: Who Is Responsible for the Genocide in Rwanda?": <http://www.wsws.org/news/1998/apr1998/rwan-a29.shtml>
"Washington backed Zaire takeover": <http://www.workersnews.flex.com.au/wn/wn050997/6zaire.html>
Lynne Duke, "U.S. Military Role in Rwanda Greater Than Disclosed," _Washington Post_ 16 August 1997, A01:
"U.S. policy in Rwanda is aimed at stabilizing the military. Although Rwanda is small and of no direct strategic value to the United States, recent events have demonstrated that "if Rwanda is unstable, that's going to lead to instability throughout Central Africa," the Pentagon official said. Indeed, Hutu refugees and militiamen have turned up not only in the former Zaire, but also in Tanzania, the Central African Republic, the neighboring Republic of Congo and on the Angolan border.
But another Washington official involved with Africa policy contended that the United States is focusing disproportionate military assistance on Rwanda as part of the creation of a "zone of influence" in East Africa, where Rwanda -- because of its troubles -- emerged as "a target of opportunity." The United States also has close relations with Uganda, Ethiopia and Eritrea -- each of which also played a key role in the Zairian insurgency, as did Angola.....
...Before the 1994 civil war, Kagame received U.S. training at Fort Leavenworth, Kan...."
After the end of the Cold War, the US government figured that it wanted a new set of African leaders (like Kagame & Kabila) to replace the old set (Habyarimana & Mobutu), whilst diminishing the influence of Belgium & France in Africa. The U.N is to be used to create a fictional "guilt of appeasement" and hence a great pretext for future wars (in case more explicit interventions are necessary).