© Yuri Gripas / Reuters
U.S. Secretary of State Rex Tillerson.
US Secretary of State Rex Tillerson says the "reign of the Assad family" in Syria is coming to an end, and the "only issue is how that can be brought about."

Tillerson's comments were made following a meeting with UN envoy Staffan de Mistura in Geneva.

"The United States wants a whole and unified Syria with no role for Bashar al-Assad in the government," Tillerson said, as quoted by Reuters. "The reign of the Assad family is coming to an end. The only issue is how that should that be brought about."

The secretary said he reaffirmed Washington's commitment to revive the Geneva peace process for Syria during a meeting with de Mistura.

He also said that "the only reason Syrian forces have been successful has been because of the air support they have received from Russia."

At the very beginning at his term as secretary of state, Tillerson said that the fate of Syrian President should "be decided by Syrian people," signaling late in March an apparent drift from the "Assad must go" narrative which prevailed during the Obama era.

Tillerson, however, changed his stance a week later in April, following the chemical attack in Idlib, which was attributed by Western powers, without any investigation, to the Syrian government.

"There is no doubt in our minds, and the information we have supports, that the Syrian regime under the leadership of Bashar al-Assad are responsible for this attack," Tillerson said back then.

The US stance then effectively reverted to the position voiced years ago by then-President Barack Obama back in 2011, who listed the ousting of Syria's president as one of the main preconditions for establishing peace in Syria.

"The transition to democracy in Syria has begun and it's time for Assad to get out of the way," Obama said in a statement when the war in Syria was only beginning. "For the sake of the Syrian people, the time has come for President Assad to step aside."

Moscow has repeatedly stated that the fate of President Assad can only be decided democratically by the Syrian people, following the defeat of the terrorist groups in Syria and peace talks between the government and the moderate opposition.