Vietnam War

===Cambodia===
{{Main|Operation Menu|Operation Freedom Deal|5=Cambodian Civil War}}
[[File:Vietconginterrogation.jpg|thumb|upright|An alleged Viet Cong captured during an attack on an American outpost near the Cambodian border is interrogated.]]

Prince [[Norodom Sihanouk]] had proclaimed Cambodia neutral since 1955,<ref>{{Cite journal |last=Sihanouk |first=Prince Norodom |title=Cambodia Neutral: The Dictates of Necessity |journal=Foreign Affairs |volume=1958 |pages=582–583}}</ref> but permitted the PAVN/Viet Cong to use the port of [[Sihanoukville Autonomous Port|Sihanoukville]] and the [[Sihanouk Trail]]. In March 1969 Nixon launched a massive secret bombing campaign, called [[Operation Menu]], against communist sanctuaries along the Cambodia/Vietnam border. Only five high-ranking congressional officials were informed of Operation Menu.{{Refn|group="A"|They were: Senators [[John C. Stennis]] (MS) and [[Richard B. Russell]] Jr. (GA) and Representatives [[Lucius Mendel Rivers]] (SC), [[Gerald R. Ford]] (MI) and [[Leslie C. Arends]] (IL). Arends and Ford were leaders of the Republican minority and the other three were Democrats on either the Armed Services or Appropriations committees.}}

In March 1970, Prince [[Cambodian coup of 1970|Sihanouk was deposed]] by his [[pro-American]] prime minister [[Lon Nol]], who demanded that North Vietnamese troops leave Cambodia or face military action.<ref>{{Cite book |last=Sutsakhan |first=S. |url=https://www.vietnam.ttu.edu/star/images/239/2390505001A.pdf |title=The Khmer Republic at War and the Final Collapse |date=1987 |publisher=United States Army Center of Military History |page=42 |archive-url=https://web.archive.org/web/20190412060055/https://www.vietnam.ttu.edu/star/images/239/2390505001A.pdf |archive-date=12 April 2019 |url-status=dead}}</ref> Lon Nol began rounding up Vietnamese civilians in Cambodia into internment camps and massacring them, provoking harsh reactions from both the North Vietnamese and South Vietnamese governments.<ref>{{Cite book |last1=Lipsman |first1=Samuel |url=https://archive.org/details/fightingfortime00lips/page/145 |title=The Vietnam Experience Fighting for time |last2=Doyle |first2=Edward |date=1983 |publisher=Boston Publishing Company |isbn=978-0-939526-07-9 |page=[https://archive.org/details/fightingfortime00lips/page/145 145]}}</ref> In April–May 1970, North Vietnam invaded Cambodia at the request of the [[Khmer Rouge]] following negotiations with deputy leader [[Nuon Chea]]. Nguyen Co Thach recalls: "Nuon Chea has asked for help and we have liberated five provinces of Cambodia in ten days."<ref>{{Cite book |last=Susan E. Cook |url=https://gsp.yale.edu/genocide-cambodia-and-rwanda-0 |title=Genocide in Cambodia and Rwanda |date=2004 |publisher=Yale University |series=Yale Genocide Studies Program Monograph Series |page=54|archiveurl=https://web.archive.org/web/20230409052610/https://gsp.yale.edu/genocide-cambodia-and-rwanda-0|archive-date=April 9, 2023}}</ref> U.S. and ARVN forces launched the [[Cambodian Campaign]] in May to attack PAVN and Viet Cong bases. A counter-offensive in 1971 as part of [[Operation Chenla II]] by the PAVN would recapture most of the border areas and decimate most of Lon Nol's forces.

The U.S. incursion into Cambodia sparked [[Protests against the Vietnam War|nationwide U.S. protests]] as Nixon had promised to deescalate the American involvement. [[Kent State shootings|Four students were killed by National Guardsmen]] in May 1970 during a protest at [[Kent State University]] in [[Ohio]], which provoked further public outrage in the United States. The reaction to the incident by the Nixon administration was seen as callous and indifferent, reinvigorating the declining anti-war movement.<ref name=Daddis/>{{Rp|128–129}} The U.S. Air Force continued to heavily bomb Cambodia in support of the Cambodian government as part of [[Operation Freedom Deal]].