Sen. Lindsey GrahamLindsey GrahamSenators to Obama: Make 'timely' call on Afghan troops levels Senate amendments could sink email privacy compromise Trump: Romney 'walks like a penguin' MORE (R-S.C.) wants to know if the military would carry out orders illegal under international law after GOP presidential front-runner Donald TrumpDonald TrumpTrump slams 'totally biased' judge in Trump U case Ex-pharma CEO Martin Shkreli: I didn’t endorse Trump Five things Clinton needs to do to win the California primary MORE suggested it would if he wins the White House.
Graham asks: Would military break law under Trump?
Graham, who put national security at the center of his failed White House bid, sent a letter Friday to Gen. Joseph Dunford, the chairman of the Joint Chiefs of Staff, about potential future presidential orders to intentionally target terrorists' families or reinstate waterboarding.
"If issued orders to target noncombatants, including children, or to use waterboarding or other extreme interrogation techniques, would you view these orders as lawful?" Graham asked in the letter.
He also wants to know what advice Dunford would give to troops asked to carry out the actions.
Trump raised eyebrows late last year when he suggested that the United States should kill family members of terrorists. Shortly after his comments, legal experts told Politifact that initially targeting family members would violate the Geneva Conventions.
He has also, as recently as Thursday's GOP debate, spoken of reinstating waterboarding and interrogation techniques that are "a hell of a lot worse," though the Senate passed an amendment that banned brutal interrogation techniques widely classified as torture as part of an annual defense policy bill.
Trump's comments sparked debate over whether or not the military would carry out his orders under a hypothetical Trump administration, with the businessman suggesting Thursday that the military wouldn't refuse him.
The GOP front-runner, however, walked back his comments Friday.
"I will not order a military officer to disobey the law. It is clear that as president I will be bound by laws just like all Americans and I will meet those responsibilities," he told The Wall Street Journal.
Graham also asked Dunford to weigh in on the legality of targeting terrorists families and waterboarding, and what impact such techniques would have on the "war effort."