US president Donald Trump is reportedly considering military action in Syria in retaliation for this week's horrific chemical attack.
A source told CNN Mr Trump had discussed possible actions with Defence Secretary James Mattis, whose judgement he is relying on, but hasn't decided what to do.
US officials told CNN the Pentagon has long-standing options to strike Syria's chemical weapons capability. These have been presented to the administration.
It comes after President Trump condemned the strike on rebel-held Khan Sheikhun, which left 86 dead, and dozens convulsing and foaming at the mouth.
"It crossed a lot of lines for me," Mr Trump said at a joint White House news conference with Jordan's King Abdullah on Wednesday.
"When you kill innocent children, innocent babies, little babies ... that crosses many, many lines, beyond a red line, many, many lines. I will tell you, it's already happened, that my attitude towards Syria and Assad has changed very much ... You're now talking about a whole different level."
The only reason President Obama wants to attack Syria is to save face over his very dumb RED LINE statement. Do NOT attack Syria,fix U.S.A.— Donald J. Trump (@realDonaldTrump) September 5, 2013
It's an about-face from President Trump, who in 2013 urged then-president Barack Obama not to intervene against President Bashar al-Assad after a major suspected chemical attack.
Mr Trump on Wednesday did not go into detail about what a US response to the atrocity would be - and he has previously opposed deeper US military involvement in Syria's civil war.
Previously, the White House had said its sole focus in Syria was defeating the jihadist Islamic State, not on ending Assad's civil war against opposition fighters.
AUTOPSIES CONFIRM CHEMICAL WEAPONS
Autopsies of three Syrians have confirmed that chemical weapons were used by Assad's regime in the horrific attack.
Justice Minister Bekir Bozdag said the World Health Organisation supervised the autopsies after almost 60 victims from Tuesday's atrocity were evacuated to his country for treatment. Three of them died.
"Autopsies were carried out on three of the bodies after they were brought from Idlib. The results of the autopsy confirms that chemical weapons were used," he said. "This scientific investigation also confirms that Assad used chemical weapons."
The deaths sparked international outrage at Assad's regime, but his government continued to deny it carried out the chemical attack in the Idlib province town.
Syrian Foreign Minister Walid Moallem insisted to reporters in Damascus that the government never used - and will not use - chemical weapons.
"I stress to you once again: the Syrian army has not, did not and will not use this kind of weapons - not just against our own people, but even against the terrorists that attack our civilians with their mortar rounds," Mr Moallem said.
He reiterated the country's contention that the deaths occurred when a Syrian air strike hit a rebel warehouse containing "toxic substances."
RUSSIA: SYRIA SUPPORT NOT UNCONDITIONAL
Longtime ally Russia described the events in Khan Sheikhun as a "monstrous crime," but said there was no "realistic, verified information."
"Any data that the American side or our colleagues in other countries could have cannot be based on objective materials or evidence," Kremlin spokesman Dmitry Peskov told reporters.
However he also said support for Assad was not unconditional. Moscow, Assad's key backer, has been supporting the Syrian government militarily since 2015.
It came as Russian President Vladimir Putin warned against apportioning blame for a chemical weapons attack in Syria until an investigation has been carried out.
In a phone call with Israel's prime minister on Thursday, Mr Putin "underlined that it's unacceptable to make unfounded accusations against anyone until a thorough and unbiased international investigation," according to the Kremlin.
KHAN SHEIKHUN REELS FROM ATTACK
An AFP correspondent in Khan Sheikhun on Wednesday said the town was reeling, with dead animals lying in the streets and residents still shell-shocked after watching their entire families die.
"Nineteen members of my family were killed," 28-year-old Abdulhamid said in the town, surrounded by mourning relatives.
"We put some masks on but it didn't do anything ... People just started falling to the ground," said Abdulhamid, who lost his twin children and wife in the attack.
Turkish President Recep Tayyip Erdogan, a vocal critic of Assad, called the Syrian president a "murderer" on Wednesday after denouncing the world's "silence" on the deaths.