Special envoy Staffan de Mistura told the UN Security Council that he was ready to convene a new round of talks in May but that US-Russian cooperation was needed.

US Secretary of State Rex Tillerson said Wednesday there was a “low level of trust” between Moscow and Washington after talks with his Russian counterpart Sergei Lavrov.

“There is a low level of trust between our two countries,” Tillerson said at a news conference following the talks. “The world’s two foremost nuclear powers cannot have this kind of relationship.”

US, Russia must agree on Syria: UN envoy

The United Nations peace envoy for Syria on Wednesday urged the United States and Russia to agree on a way forward to end the war in Syria and pave the way for a “real negotiation.”

Special envoy Staffan de Mistura told the UN Security Council that he was ready to convene a new round of talks in May but that US-Russian cooperation was needed.

His appeal came as Tillerson was in talks in Moscow with his Russian counterpart Lavrov following US missile strikes in Syria in retaliation for a suspected chemical attack.

The two countries have “serious differences” but also a “common interest” in ending the six-year war that has killed 320,000 people, De Mistura said.

“They must find a way to work together to stabilize the situation in a deliberate, realistic and concerted way in support of the political process,” he said.

The United Nations is ready to lead a “real negotiation” on a “package for an orderly, mapped-out, credible and irreversible, agreed political transition” to end the war, he added.

The council was meeting ahead of a vote later in the day on a draft resolution demanding that the Syrian government cooperate with an investigation of the suspected chemical attack in the rebel-held town of Khan Sheikhun.

Russia is expected to veto the measure — which would mark the eighth time that Moscow has used its veto power to block Security Council action directed at its ally, Syria.

“Let us view this moment of crisis — and it is a moment of crisis — as a watershed and an opportunity for a new level of seriousness in the search for a political solution,” said De Mistura.