United States President Barack Obama addresses the 70th session of the United Nations General Assembly at U.N. headquarters, Monday, Sept. 28, 2015.

U.S. President Barack Obama on Monday called for a “managed transition” in Syria apart from Syrian President Bashar al-Assad, whom he accused of killing children and creating the turbulence that unleashed the ongoing four-year bloody conflict.

Obama took the podium at the U.N. General Assembly to denounce those who support leaders like Assad, accusing him of slaughtering children.

The barb, a direct attack on Russia and Iran for their ongoing military backing for Syria’s beleaguered regime, came shortly before Moscow’s President Vladimir Putin was to speak.

Obama said some states prefer stability over the international order mandated by the U.N. Charter, and try to impose it by force.

“We’re told that such retrenchment is required to beat back disorder, that it’s the only way to stamp out terrorism or prevent foreign meddling,” he said.

“In accordance with this logic, we should support tyrants like Bashar al-Assad who drops barrel bombs to massacre innocent children, because the alternative is surely worse.”

Russia and Iran have argued that world powers should support Assad’s regime, at least until Syrian forces manage to defeat ISIS jihadist group.

Obama said he was nevertheless “prepared to work with any nation, including Russia and Iran, to resolve the conflict.”

Syria, ISIS ‘not one nation’s affair’

“When a dictator slaughters tens of thousands of its people, it is not one nations’ affair, but it brings magnitude of suffering of all, likewise when a terrorist group beheads captives, it is not one single nations problem but it is an assault on all humanity,” Obama said.

He added: “I said before and I will repeat there is no room to an apocalyptic cult like ISIS.”

He vowed that there will be no safe haven for “cults” like ISIS.

Unlike some Western leaders who green-lighted Assad as part of the political transition in the war-torn country, Obama thought otherwise.

He also said the U.S. is prepared to work with any nation, including Iran and Russia, to resolve the Syria crisis.

Obama backs U.N. values

Obama, meanwhile, lashed out at powers who want to take the world to the “old ways,” rejecting the use of “coercion” and force by bigger countries against smaller ones during his U.N. address on Monday, in an indirect reference to Russia supporting the Syrian regime.

“I lead the strongest military in the world ever known,” Obama said, adding that he could act “unilaterally,” “by force when necessary” but “I stand before you… I believe we the nations of the world cannot turn to the old ways of coercion.”

While Obama said it is worth reflecting over what the U.N. has achieved, the U.S. president said the U.N. charter – which buttressed universal human rights in 1945 – should be protected.

He also criticized powers, who are centered around “zero-sum games” want to “predate” by going back to such achievement.

He said “we live in an integrated world,” and success of nations depends on their people.