Russia's Lavrov and US Tillerson spoke by phone about situation in Syria

Donald Trump Xi Jinping

Separately, on CBS News' Face The Nation, Mr Tillerson said the first priority for the USA remains defeating the Islamic State in Iraq and Syria (ISIS).

It prompted President Donald Trump to retaliate by firing 59 cruise missiles at the Syrian airbase where the U.S. believes the gas attack was launched.

But Russia and Syria's other key ally, Iran, on Saturday vowed to continue fighting in the country after army chiefs General Valery Gerasimov and Major General Mohammad Bagheri spoke by phone.

On the same day, Haley said, "Our priority is no longer to sit and focus on getting Assad out".

"We want to continue our efforts with Russian Federation in the Astana process in terms of measures to increase trust and establish a cease-fire", he told reporters in Antalya, according to the Anadolu state news agency.

Rouhani also condemned use of chemical weapons in Syria, saying it was "regrettable". He said that for that "this oppressive Assad needs to go".

Russian Federation maintains a close political and military alliance with President Bashar Assad's government and has been accused of supporting its attacks against Syrians opposed to Assad's rule - something Moscow adamantly denies.

In a statement carried by Iranian state television, President Hassan Rouhani called Saturday for the formation of an global fact-finding committee that "must not be headed by Americans".

But the Russian Defense Ministry said on Wednesday that the deadly gas contamination was caused by the explosion of chemical weapons produced and stored by the rebels, after Syrian aircraft bombed the area.

"Russia could be part of the solution", he said, noting that now they were "part of the problem". Assad accused the USA of trying to boost the morale of "terror groups" in Syria.

"It agreed to be the guarantor of the elimination of the chemical weapons, and why Russian Federation has not been able to achieve that is unclear to me", Tillerson said.

He had planned to travel to Russia Monday on a trip meant to start a fresh dialogue with Moscow.

He said the United Kingdom continues to "deplore" Moscow's defence of Mr Assad's regime as he pulled out of talks with Russian counterpart Sergey Lavrov.

Stunning and brazen, naturally, but still better than President Putin's Friday condemnation of the U.S. airstrike as "aggression against a sovereign state in violation of the norms of worldwide law".

Turkey's Foreign Minister Mevlut Cavusoglu said Ankara sees the US intervention in Syria as appropriate but not enough.

"What America waged in an aggression on Syria is a crossing of red lines".

The new developments come after the USA launched 59 Tomahawk missiles from its warships positioned in the eastern Mediterranean. The groups Raqqa is Being Slaughtered Silently and Sound and Picture said the attack killed a woman and her six children.

Rouhani added the US attack was in line with policy to strengthen the terrorists.

"Those attacks did not reduce the regime's ability to kill civilians".

On Friday morning, the United States launched 59 Tomahawk missiles from its warships in the eastern Mediterranean, targeting Syria's Shayrat airbase near Homs.

But what many found puzzling was that the attack on Idlib was different only in degree from what Assad's regime has been doing, with some consistency, for years.