US President Donald Trump ‘changed’ by Syrian chemical attack

US President Donald Trump has branded the Syrian chemical attack an "affront to humanity" which changed his view of the country’s Russian-backed leader, as the US ambassador to the UN warned of unilateral American action.

President Trump said the strike on the rebel-held town of Khan Sheikhun that killed at least 72 people crossed "a lot of lines" and "cannot be tolerated".

He warned the attack had changed his view of Syrian President Bashar al-Assad, but would not publicly comment on actions he may authorise against him.

Previously, the White House has said its sole focus in Syria was defeating the jihadist Islamic State group, not on ending Assad’s civil war against opposition fighters. But Mr Trump and other senior US officials said that the latest attack had changed the calculus.

Mr Trump also renewed his criticism of his predecessor Barack Obama who in 2013 famously failed to take action after Assad crossed a "red line" with a previous chemical attack.

"It crossed a lot of lines for me," Mr Trump said, at a joint White House news conference with Jordan’s King Abdullah yesterday.

"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."

Mr Trump did not go into detail about what a US response to the atrocity will be -- and he has previously opposed deeper US military involvement in Syria’s civil war.

The father cradled his 9-month-old twins, Aya and Ahmed, each in an arm. He stroked their hair and choked back tears, mumbling, "Say goodbye, baby, say goodbye" to their lifeless bodies.

Abdel Hameed Alyousef lost his two children, his wife and other relatives in the suspected chemical attack Tuesday in the northern Syrian town of Khan Sheikhoun.

In footage shared with The Associated Press, Alyousef sits in the front seat of a van with the twin, his eyes red as he asks his cousin Alaa to video his farewell to them.

When the airstrike took place, "I was right beside them and I carried them outside the house with their mother,"Alyousef, a 29-year-old shopowner, told the AP.

"They were conscious at first, but 10 minutes later we could smell the odor." The twins and his wife, Dalal Ahmed, fell sick.

He brought them to paramedics and, thinking they would be OK, went to look for the rest of his family.

He found the bodies of two of his brothers, two nephews and a niece, as well as neighbors and friends. "I couldn’t save anyone, they’re all dead now," he said.

Only later was he told his children and wife had died.

"Abdel Hameed is in very bad shape," his cousin Alaa said. He’s being treated for exposure to the toxin. "But he’s especially broken down over his massive loss."

US Ambassador to the UN, Nikki Haley, has warned that the Trump administration will take action against chemical attacks in Syria that bear "all the hallmarks" of Assad’s government if the UN Security Council fails to act.

"When the United Nations consistently fails in its duty to act collectively, there are times in the life of states that we are compelled to take our own action. For the sake of the victims, I hope the rest of the council is finally willing to do the same," she said.

Ms Haley urged the council at an emergency meeting to immediately approve a resolution drafted by the US, Britain and France that condemns and threatens consequences for the use of chemical weapons, especially in Tuesday’s attack that killed dozens of people in rebel-held Idlib province.

Ms Haley’s decisive comments came after Russian Foreign Ministry spokeswoman Maria Zakharova announced Moscow’s opposition to the draft resolution. She called it "categorically unacceptable" because "it runs ahead of the investigation results and names the culprit, Damascus."

"The main task now is to have an objective inquiry into what happened," Russia’s deputy U.N. ambassador Vladimir Safronkov told the Security Council.

"Up to now all falsified reports about this incident have come from the White Helmets or the Syrian Observatory for Human Rights based in London which have been discredited long ago."

But holding up photos of victims of the attack, Ms Haley accused Russia of blocking action and closing its eyes to the "barbarity" of three previous chemical attacks that investigators blamed on the Syrian government by vetoing a resolution in late February that would have imposed sanctions on those responsible.

"The truth is that Assad, Russia, and Iran have no interest in peace," she said.

"The illegitimate Syrian government, led by a man with no conscience, has committed untold atrocities against his people for six years."

Distressing images emerged after the air strikes showing dozens of people dead and injured lying on the ground across the rebel-held town of Khan Sheikhun, including children unable to breathe and foaming at the mouth.

The gas is suspected to be a nerve agent, with investigators considering whether it may be deadly saran gas, which was used to kill 1300 people in rebel-held parts of the capital Damascus in 2013.

The West, including Australia, the UK, the US and the EU, immediately pointed the finger at those in the Assad regime for the attacks, as did the Syrian opposition parties.

Pro-Assad forces "categorically denied" responsibility and blamed the opposition, undeterred by the fact the rebels do not have an air force.

The Russian defence ministry, which is backing Assad by targeting Islamic State and other rebels, said it did not have planes operating in the area and suggested the rebels were to blame because the air strikes may have hit "a workshop for the production of landmines filled with poisonous substances".

The chemical attack is another appalling low point in the six-year Syrian civil war, and was followed up by the bombing of one of the hospitals that was treating the sick and injured from the chemical attack.

Citizens filmed dead children and adults being placed on to the backs of trucks, while under-equipped emergency workers tried to ease the suffering of the injured by hosing them with water.

Some of those poisoned by the gas were taken to hospital in Turkey, with the border a relatively short distance away from Khan Sheikhun.

Charity Save the Children said 11 children were among the 58 confirmed dead, with another 100 people injured, some critically.

Prime Minister Malcolm Turnbull and Foreign Minister Julie Bishop issued a statement condemning "in the strongest possible terms" the chemical weapons attack, which happened at dawn on Tuesday.

"The use of chemical weapons is illegal and abhorrent," they said.

"While the full facts are still to be determined, if the Assad regime is responsible for this attack those who approved and deployed these weapons must be held accountable."

The pair supported an urgent UN debate on the attacks and called for a further, independent investigation.

Australia is one of the countries which is bombing parts of Syria and Iraq in the fight against rebel group Islamic State, and has previously called for Assad to be removed, but has since modified its stance to say the despotic president may have to be part of the transition to new leadership.

Mr Turnbull and Ms Bishop also called on pro-Assad Russia and Iran to "pressure the Assad regime to cease illegal, chemical attacks on its own people".

Australia will support any further sanctions against Syria passed by the UN.

World leaders have condemned the chemical attack, with most blaming Assad’s regime.

UK Prime Minister Theresa May said: "I’m very clear that there can be no future for Assad in a stable Syria which is representative of all the Syrian people."

British Foreign Secretary Boris Johnson said "all the evidence" he had seen so far "suggests this was the Assad regime who did it in the full knowledge that they were using illegal weapons in a barbaric attack on their own people." He added that he "would like to see those culpable pay a price for this."

French president Francois Hollande condemned the "war crime" and reiterated the need for an

international military campaign against Assad over his use of chemical weapons.

President Donald Trump condemned the act as "heinous" and said it could not be ignored by the "civilised world". He also laid the blame at his predecessor Barack Obama’s feet, saying it was "a consequence of the past administration’s weakness and irresolution."

German Foreign Minister Sigmar Gabriel called on Russia to endorse a planned United Nations Security Council resolution condemning the attack.

UN Secretary-general Antonio Guterres said the assault is a "moment of truth" that must be investigated.

EU Council president Donald Tusk said the Khan Sheikhun massacre is "another reminder of the brutality" of Syria’s regime

Iran’s foreign ministry spokesman Bahram Ghassemi condemned the use of chemical weapons but suggested the blame may lie with "terrorist groups", not Assad’s regime.