The United States and Russia blamed each other for Syria’s failing cease-fire Wednesday, underscoring the fractured U.N. Security Council’s inability for more than five years to stop the Arab country’s civil war.

In a public session originally envisioned to enshrine Syria’s Sept. 9 truce, world powers were left to rue the possibility of the conflict entering an even darker phase after a series of attacks on humanitarian workers.

Washington, Moscow and the council’s other nations all sought to revive the U.S.-Russian cease-fire deal, but seemed stuck on fundamental differences old and new: Who bears ultimate responsibility for the war and whose actions over the last days scuttled perhaps the best opportunity for peace?

“Supposedly we all want the same goal. I’ve heard that again and again,” a clearly angry U.S. Secretary of State John Kerry told the council, referencing oft-repeated international objectives of a united, secular and democratic Syria. “But we are proving woefully inadequate in … making that happen.”

Kerry outlined U.S. complaints against Syrian President Bashar Assad’s government and its chief backer, Russia. He recited Moscow’s changing narrative over a deadly attack this week on an aid convoy that has included claims of a justifiable counterterror strike as well as vehicles spontaneously combusting. Russia’s latest contention on Wednesday was that a U.S. coalition drone was operating in the area when the attack occurred; the Pentagon said no drone was there at the time.

“This is not a joke,” Kerry said, sharply criticizing those who engage in “word games” to dodge responsibility over questions of “war and peace, life and death.”

Kerry offered one concrete suggestion to revive diplomatic hopes, focused on protecting key aid routes in northern Syria. It was unclear if Russia and Syria would agree.

“To restore credibility, we must immediately ground all aircraft flying in those key areas in order to de-escalate the situation and give a chance for humanitarian assistance to flow unimpeded,” he said.

Kerry spoke just after Russian Foreign Minister Sergey Lavrov delivered his own set of barbs, illustrating the breakdown in trust in the 12 days since he and Kerry clinched a cease-fire agreement and a potential U.S.-Russian military partnership against the Islamic State and al-Qaida. The former Cold War foes and much of the international community hailed that earlier agreement, only to watch it unravel amid an upsurge in violence that included an accidental U.S. strike that killed more than 60 Syrian soldiers.

Unlike Kerry, who stressed the importance of Assad’s government ending military operations against rebels and allowing in unfettered aid, Lavrov said the U.S. had the biggest responsibility.

“The key priority is to separate the opposition forces from the terrorists,” Lavrov said.

Responding to the wide criticism of the convoy airstrike, which American officials are blaming on Russia, Lavrov cited various possible explanations. Twenty civilians were killed when the Syrian Red Crescent convoy was struck. Lavrov called for an independent investigation.

Lavrov was more direct in laying out what he presented as a series of truce violations by U.S.-backed rebel groups near the northern city of Aleppo. And he declared Syria’s conflict, as well as those involving Iraq, Libya and other instable nations, the “direct consequence” of foreign military interventions in the region. It was a not-so-subtle finger pointed at Washington.

Lavrov and Kerry’s speeches laid bare their widely divergent views of the Syrian war that has killed up to a half-million people, contributed to Europe’s worst refugee crisis since World War II and allowed the Islamic State to emerge as a global terror threat. At one point, Kerry said listening to his Russian counterpart was like hearing about a “parallel universe.”

On Tuesday, the two diplomats met with more than a dozen Arab and European foreign ministers, hoping to hold onto what might be salvageable from a week of relative calm in Syria. No one spoke of any progress, beyond a decision to hold follow-up discussions later this week.

Lavrov on Wednesday mentioned the possibility of a three-day period of “silence” being announced.

Syrian Ambassador Bashar Jaafari said his government was prepared to resume an intra-Syrian dialogue. He said the U.S. “disowned” the cease-fire deal.

“We are at a make-or-break moment,” U.N. Secretary-General Ban Ki-moon said, opening the session.

His peace envoy to Syria, Staffan de Mistura, described his long-delayed plans for a multi-step Syrian peace process and transition that appeared, even by his own admission, untethered to reality on the ground. Wednesday’s latest violence included an airstrike in the north that killed five medical staff, according to a relief organization.

“I know, it looks like a dream,” de Mistura said.

(AP)