John Bacon

USA TODAY

Russia should reconsider its support for Syrian President Bashar Assad in light of the apparent chemical weapons attack that killed more than 80 people and "horrified us all," Secretary of State Rex Tillerson said Thursday.

Asked at a press conference whether the U.S. would lead an international coalition to oust the Syrian leader, Tillerson replied that "those steps are underway." He said there's no role for Assad in Syria's future and reiterated his contention that "information supports" the U.S. claim that the Syrian military was responsible for Tuesday's bloody attack.

A statement released by the State Department Thursday afternoon attributed to Tillerson echoed those sentiments.

"We are considering an appropriate response for this chemical weapons attack which violates all previous U.N. resolutions, violates international norms and long-held agreements between parties, including the Syrian regime, the Russian Government, and all other members of the U.N. Security Council," the statement read. "It's a serious matter; it requires a serious response," the statement ended.

Regarding the press conference, Tillerson spoke hours after a Kremlin spokesman said Russian support for Assad in his brutal, six-year struggle to retain power is "not unconditional." The Kremlin has made similar statements in the past but remained Assad's most crucial military ally.

Dmitry Peskov, spokesman for Russian President Vladimir Putin, told the Associated Press that Moscow and the Assad regime have a strong relationship and that only Assad can keep "terrorists" from overrunning the nation scarred by the devastating civil war. But Peskov added that Moscow doesn't have the power to tell Assad what to do.

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UNICEF confirmed Thursday that at least 27 children died in the apparent chemical weapons attack, which drew global outrage as graphic pictures of dead and wounded children emerged from the scene.

The Syrian Observatory for Human Rights put the death toll at 86 — including dozens of women and children — from Tuesday's airstrikes in Syria's northwest province of Idlib, an area about 60 miles from the Turkish border where rebel forces have been conducting an offensive. Turkish officials have put the death toll at more than 100.

Another 546 people, including many children, suffered from the effects of the gas, the U.N.'s child advocacy group said.

“The killing of children in Syria cannot be allowed to continue," said UNICEF Regional Director Geert Cappelaere. He urged all parties involved in the conflict to "immediately put an end to this horror."

Syrian Foreign Minister Walid Moallem continued to reject claims that Syrian forces used chemical weapons. Moallem pressed his assertion, supported by Russia, that Syrian airstrikes using conventional weapons struck a rebel chemical weapons depot, releasing the toxic gas.

That claim has drawn scorn from the rebels and some global leaders. Tillerson reiterated "there is no doubt in our minds" that Assad's regime was responsible for the attack.

Moallem said Damascus needs assurances that any international probe of the tragedy will be objective. He accused the West of blaming the Syrian government before gathering facts in an attempt to disrupt the political process in the war-torn country.

“This choir that was launched in the international arena is made up of states that are well-known for conspiring against Syria,” he said.

Autopsies on three Syrians who died after being brought to Turkey for treatment suggest the banned nerve agent sarin was used in the attack, the Turkish Health Ministry said. The international watchdog Organization for the Prohibition of Chemical Weapons said it requested information on the attack from Syria and other parties.

Turkish President Recep Tayyip Erdoğan said his nation stands ready to support any military action the U.S. and President Trump might consider. Erdoğan described Putin's unwillingness to admit the Syrian military was responsible as "sad."

Putin discussed the attack Thursday with Israeli Prime Minister Benjamin Netanyahu, who lashed out at Assad's government after the attack.

In a statement about the call, the Kremlin said: "Putin particularly stated that it was unacceptable to bring accusations against anyone until a thorough and impartial international investigation was conducted."