(CNN) Americans shocked by tales of Russian assassinations in Ukraine and the grisly murder of Washington Post columnist Jamal Khashoggi allegedly by Saudi Arabia might consider the past history of their own government and what rules exist today to prevent a US hit job against a foreign political opponent.

Indeed, the moral debate surrounding political assassination seems murkier and more open-ended now than ever.

Two years ago, President Donald Trump appeared unperturbed during a national television interview with then Fox News commentator Bill O'Reilly when asked about doing business with Russian leader Vladimir Putin. In 2006, Putin approved a law allowing assassinations abroad, making them almost commonplace in nearby Ukraine.

"Putin's a killer," said O'Reilly.

"There's a lot of killers, we got a lot of killers," President Trump replied . "What, you think our country is so innocent?"

O'Reilly seemed taken aback. Trump persisted. "You think our country is so innocent?" the president repeated.

"I don't know of any government leaders that are killers," O'Reilly answered back.

"Well..., take a look at what we've done too," Trump assured him.

History shows America's first (known) attempt at state-sanctioned assassination began in the early 1960s when the CIA recruited two top gangsters , Sam Giancana and Johnny Roselli, to try to kill Cuba's young Communist leader Fidel Castro. The Mafia was enraged because Castro closed down their lucrative Havana casinos. And US officials worried about Castro spreading revolution throughout Latin America, becoming a puppet who obtained Russian missiles and nearly provoked an Armageddon-like nuclear war.

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However, the "Family Jewels" documents never clarified exactly what Presidents Dwight Eisenhower and John F. Kennedy knew about the Castro assassination plans during their administrations. Ironically, despite numerous failed "whack-a-mole"-like assassination attempts against him sponsored by the CIA, Castro died at age 90 in 2016.

The following year, long-held secret records about JFK's 1963 assassination were released in batches from July 2017 through April 2018 by the National Archives with Trump's approval. They provided more details about the 1960s covert war against Castro operated out of southern Florida and about America's first foray into state-sanctioned assassination.

From the very start of the Kennedy administration, records suggest, there was talk within the CIA of state-sponsored murder.

Sam Halpern, a CIA official recalled in a 1987 agency interview with historian Ralph E. Weber that, "one of the first things that John Kennedy -- John, not Robert -- asked Dick Bissell for in January 1961 after he had gotten inaugurated, one of the first things was an assassination capability." CIA records and Congressional testimony show Halpern worked with both agency deputy director Richard Bissell and William Harvey, another key CIA player in the assassination schemes. "Create one please," said the president about this foreign assassination plan, without naming a particular target, according to Halpern's secret account disclosed in 2017 under the JFK Assassination Records Collection Act.

Despite Halpern's claim, no document has been discovered with such an alleged directive by JFK. However, CIA officials from that era, like former deputy director Richard Bissell, later testified the Kennedy White House called for an "Executive Action" plan designed to depose Castro with methods that included possible assassination.

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In his 1975 congressional testimony, Bissell said "I have no direct knowledge or firsthand knowledge of his being advised, but my belief is that he [JFK] knew of it."

Bissell explained that "What they meant by an Executive Action capability of course, embraced a great deal more than assassination. It embraced means of discrediting a political leader, possibly means of physically incapacitating him but without permanent injury, possibly assassination as last resort." Notes kept by Harvey quote Bissell as telling him : "The White House has twice urged me to create such a capacity."

Defenders of Kennedy, including friends and family, later said CIA men like Halpern and Helms smeared the late president's reputation to hide their own wrongdoing. Nevertheless, documents show then US Attorney General Robert F. Kennedy remained the biggest cheerleader in the Kennedy administration's "get Castro" campaign. RFK was a prime force within a "Special Group" of White House officials who oversaw covert spy actions against Castro's regime.

While friends and former colleagues, such as historian Arthur Schlesinger, vigorously defended the fabled Camelot legacy, other admirers were at a loss to excuse the Kennedy administration's covert actions against Castro.

Historian Ronald Steel wrote , "exactly how directly involved the Kennedys were in these activities remains a matter of contention." But, Steel continued, "there is a compelling trail of circumstantial evidence."

This lack of definitive proof blurred an even larger American debate about killing political opponents abroad. In 1976, in the wake of Congressional hearings about the CIA, President Gerald Ford issued an executive order banning political assassination and condemned the practice.

Over time, however, such White House absolutes would prove malleable. Even among some Kennedy liberals, a realpolitik debate existed about political assassination. For example, in 1975 Nicholas deB. Katzenbach, a former top Justice Department official in the Kennedy administration, conceded that "if somebody had knocked off Hitler in 1936 or 1937, I think it would have been a big help."

For a generation, subsequent presidents abided by this ban on foreign assassination until the terror attacks of September 11, 2001. Like the Cold War fears of the 1960s, America suddenly placed security concerns above all. After 9/11, the US developed plans to create an assassination squad against Al-Qaeda leaders at the urging of Vice President Dick Cheney. Eight years passed until this hit squad's existence was revealed publicly in 2009.

Once more, America debated political assassination. After the killing of 9/11 mastermind Osama bin Laden during a 2011 US raid in Pakistan to capture him, some questioned its legality, but American officials called it a military action against an ongoing enemy combatant rather than a prohibited act of assassination.

Today, world leaders are now armed with evermore-sophisticated high-tech killing devices -- such as drones, spray devices, and biological, radiological elements that can kill without a trace. But will future threatening figures like bin Laden be considered terrorists or political leaders -- and would policy favor assassination if it was a preemptive strike that prevented mass casualties?

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"Does the United States want to return to this era of uncertainty?" wrote former presidential advisers Mark Medish and Joel McCleary in 2010, recalling the CIA's Castro murder scheme. "Do democratically elected leaders wish to open this bloody door again, when in fact their own protection is as porous and precarious as ever? Technology has made assassination, as well as escalatory and asymmetrical reprisals, easier than ever."

During this Trump era, political assassinations in Ukraine and the Khashoggi killing raise serious questions about how the White House might respond in the future. Would Trump ever consider political assassination against a foreign leader perceived as a threat to the United States? And would the Congress and the American people tolerate such an action?

The need for more debate about political assassination and tighter scrutiny by governments seems more apparent than ever.