A new book on US president Dwight Eisenhower’s diplomatic manoeuvres in Cambodia pulls back the veil on the US government’s unrelenting efforts to break Prince Norodom Sihanouk’s political neutrality during the Cold War.

The book, Eisenhower and Cambodia, published last year by Southeast Asia expert William Rust, unveils the minutiae of the administration’s dealings with Cambodia using previously untapped primary sources.

The book focuses on Sihanouk’s efforts to exert Cambodia’s political neutrality in the wake of the 1954 Geneva Accords, fostering a relationship with China, the US and the Soviet Union in an attempt to stave off coup and assassination attempts from Thailand and Saigon.

The book explores the extent of US involvement in the attempts against Sihanouk. US-Cambodia relations were severely damaged in 1959 when CIA support for warlord Dap Chhuon’s attempt to overthrow Sihanouk was exposed.

“[Chhuon] received money and communications equipment from a CIA officer who operated in the US Embassy under a diplomatic cover,” said Julio Jeldres, a biographer and longtime confidant of Sihanouk. “There was also the bombing of the Royal Palace, organised by South Vietnamese intelligence, which was then monitored by the CIA.”

According to Rust, Eisenhower sought to rid Cambodia of Sihanouk because he refused to join the US fight against communism.

“From the Eisenhower administration’s point of view, the basic problem with Sihanouk was his indifference to the global ideological struggle between the ‘communist bloc’ and the ‘free world’,” Rust wrote.

In a recent book review published by the London School of Economics, acclaimed journalist Elizabeth Becker, who launched her career covering war in Cambodia, noted that much has been written about Richard Nixon’s disastrous interventions in Cambodia, but little on Eisenhower’s role.

Eisenhower had a reputation in foreign policy circles as a moderate who practised restraint in international interventions, Becker writes. But things were different in Indochina. “Eisenhower’s policy towards Cambodia was an unbending ‘Us versus Them’ ideology with no room for outliers,” she wrote.

According to Becker, Rust employs “impressive documentation” to illustrate the dynamics at the beginning of the war between Vietnam and the US. “While the outline of this history has been known, there was some question over US responsibility,” Becker wrote. “Rust’s work eliminates any idea of American innocence.”