Tillerson: Asking for favors, withholding assets ‘wrong'

(CNN) - Former Secretary of State Rex Tillerson said Monday that "clearly asking for personal favors and using United States assets as collateral is wrong," a swipe at President Donald Trump as the investigation into his dealings with Ukraine intensifies.

PBS Newshour's Judy Woodruff asked Tillerson at an event in Texas what he would have done if -- while he was secretary of state -- US military assistance to Ukraine had been made conditional on the launching of a political investigation, which is what House Democrats accuse Trump of having done.

"I'd rather not answer a hypothetical on something that's so visible in the hearings today," he said initially.

When Woodruff pressed him on it, he replied, "Clearly, asking for personal favors and using United States assets as collateral is wrong."

"There's just no two ways about it -- so if you're seeking some kind of personal gain and you're using whether it's American foreign aid or American weapons or American influence, that's wrong," Tillerson continued. "And I think everyone understands that."

Tillerson appears to have prevented some potentially troubling dealings initiated by those later found to be central to the Ukraine saga.

CNN reported last month that Rudy Giuliani, Trump's personal lawyer, used a 2017 Oval Office meeting with Trump to press Tillerson, then-secretary of state, to support a prisoner swap to resolve the Justice Department's prosecution of a Turkish businessman accused of violating Iran sanctions, a person briefed on the meeting tells CNN. After the meeting Tillerson mentioned the discussion to then-chief of staff John Kelly, who was not in the meeting, noting that it was a deal he could not support.

Tillerson's relationship with Trump was in the news more recently when former UN Ambassador Nikki Haley accused both Tillerson and Kelly of looking to undermine Trump in an effort to "save the country" in her new memoir. She also wrote that Tillerson also told her people would die if Trump was unchecked. Tillerson has denied her claims.

CNN's Evan Perez, Kevin Liptak and Jamie Ehrlich contributed to this report.