Retired senior military officers and human rights advocates are reacting with disgust at Republican presidential frontrunner Donald Trump’s description of the Geneva conventions as a “problem” for the conduct of US wars.

At an appearance in Wisconsin on Wednesday that was obscured by his suggestion that women who choose abortion should face punishment, Donald Trump was also quoted as saying: “The problem is we have the Geneva conventions, all sorts of rules and regulations, so the soldiers are afraid to fight.”

Trump has previously advocated killing the families of terror suspects; torture “a hell of a lot worse” than waterboarding; and widespread bombing campaigns against Islamic State, which operates in civilian-packed areas. The Geneva conventions provide the basis for protections against war crimes, privileging the status of civilians and detainees during wartime.

Several retired officers said the comments called into question Trump’s fitness to serve as commander-in-chief, saying that service members operating in line with his predilections would be tasked with behavior ranging from the disgraceful to the illegal.

“Donald Trump cannot possibly understand [Geneva] because he has neither the experience, the expertise or the moral compass to grasp it,” said Steve Kleinman, an air force reserve colonel and an interrogations expert.

Geneva is “a fundamental moral and tactical construct that serves as a foundation for the law of armed conflict, because all wars, including the global war on terror, come to an end. We as a community of nations need to engage with one another and not be separated by horrible, immoral treatment of one side over another,” Kleinman said.

“America’s military men and women swear to support and defend the constitution, including our obligations to adhere to treaties on the treatment of non-combatants,” said Paul Yingling, a retired US army colonel.

Now a high school teacher in Colorado, Yingling, was the deputy commander of the armored cavalry regiment that recaptured the Iraqi city of Tall Afar from insurgents. He gained renown in military circles by criticizing the general officers who presided over the deterioration of the Iraq war.

“Prisoners of war and the family members of suspected terrorists are noncombatants. Torturing and murdering noncombatants are the actions of criminals and cowards. America’s military men and women are neither,” Yingling said.

Christopher Harmer, a former navy pilot and current analyst at the Institute for the Study of War, said Trump’s dismissal of Geneva demonstrated he was “monumentally unprepared” for the White House.

“From advocating the assassination of women and children whose only crime is being related to terrorists, to speaking glibly of carpet bombing entire swaths of the Middle East, to opining that Japan, South Korea and Saudi Arabia should obtain nuclear weapons, Donald Trump comes across exactly as what he is: a reality TV star who has no idea about how US national security actually works in practice,” Harmer said.

“His candidacy is merely an embarrassment to the United States; if he were to actually become president, the damage he would do to our strategic relationships with our allies would be immense.”

Representatives of human rights groups sounded similar notes.

Laura Pitter, a national security lawyer with Human Rights Watch, observed that Geneva protections are “deeply ingrained and institutionalized” in US military culture.

“At least he recognizes the Geneva conventions would prohibit waterboarding. I suppose that’s a step in the right direction,” Pitter said.

Wells Dixon of the Center on Constitutional Rights did not wish to comment specifically on Trump but called the Geneva conventions “essential” to preventing “the sort of atrocities that occurred during World War II”.

Dixon continued: “Today the United States relies on the Geneva conventions to ensure our collective security and protect our soldiers who may fall into enemy hands. The Geneva conventions are essential to ensuring the protection of both combatants and civilians during armed conflict.”

Trump’s campaign did not respond to a request for clarification of his Geneva comments.

“The belief that torture works is based on American television programs,” Yingling said.

“As a veteran of five tours in combat and a former counterterrorism instructor, my experience is limited to reality.”