The White House says President Donald Trump is not responsible for the chemical weapons attack in Syria - Barack Obama is.

'President Obama said in 2012 that he would establish a "red line" against the use of chemical weapons and then did nothing,' White House Press Secretary Sean Spicer told reporters Tuesday morning.

Trump's administration last week said it was no longer a 'priority' of the United States to boot Syrian dictator Bashar al-Assad from power. Instead, it said would apply pressure to Assad to make changes inside his country.

Tuesday Assad was accused of using sarin gas against his own people, killing at least 70 civilians, including 11 children.

The White House says President Donald Trump is not responsible for the chemical weapons attack in Syria - Barack Obama is. 'President Obama said in 2012 that he would establish a "red line" against the use of chemical weapons and then did nothing,' Donald Trump's spokesman said

Despite the timing, Spicer said blame for the atrocity does not lie with the current administration.

'These heinous actions by the Bashar al-Assad regime are a consequences of the past administration’s weakness and irresolution,' the Trump spokesman said during a non-televised briefing.

He would not say how the United States plans to respond, contending that he'd 'rather not get ahead' of the national security team.

But he said the chemical weapons attack 'is not something that any civilized nation should sit back and accept or tolerate.'

The White House official at the same time denied that the administration is comfortable with Assad staying in power.

'I think the president is extremely alarmed at these revelations,' he said.

Syrian opposition activists have claimed the chemical attack was caused by an airstrike carried out either by President Assad's forces or Russian warplanes. Russia's military said its planes did not carry out any strikes near the town.

It is believed that 400 people were injured after being exposed to toxins during the attack in addition to the more than 70 who were killed.

A formal statement from the White House on the attack derided Assad for using chemical weapons 'against innocent people, including women and children. It did not mention Russia.

'We feel very confident in the statement that we're making,' Spicer said.

Trump's administration last week said it was no longer a 'priority' of the United States to boot Syrian dictator Bashar al-Assad from power. Instead, it said would apply pressure to Assad to make changes inside his country

Assad's behavior is 'reprehensible and cannot be ignored,' the president's spokesman said, reading it off at the top of his Tuesday briefing.

It went on to lambaste Obama for his infamous 'red line' threat in 2012 that he never acted. His administration argued that there was no military solution in Syria and tried to remove Assad through diplomatic negotiations instead.

'What's the point of red lines? America's credibility was at stake, and I think the president wants to point out that there was a red line, and they did cross it, and we did have alternatives to regime change, and they weren't taken,' Spicer later explained.

US Ambassador to the United Nations Nikki Haley said last Thursday that the United States was shifting from the Obama administration's approach and was not 'going to sit there and focus on getting [Assad] out.'

Haley, who just took the reigns of the UN Security Council, said Monday, 'We have no love for Assad. We’ve made that very clear.

'We think that he has been a hindrance to peace for a long time. He’s a war criminal. What he’s done to his people is nothing more than disgusting,' she said.

Spicer said Tuesday the administration's new tact reflects the current 'political reality.'

At least 100 people have died from suffocation after a toxic gas attack in the town of Khan Sheikhoun, in the rebel-held central province of Idlib, Syria, early Tuesday morning. Pictured above, a child gets treatment at a hospital after Assad Regime forces attacked

At least 11 of the more than 70 perople people who died in the chemical attack were children. Doctors treating victims at makeshift hospitals in the area say dozens of victims from Khan Sheikhoun are showing signs of sarin poisoning

Doctors treating victims at makeshift hospitals say dozens of victims from Khan Sheikhoun are showing signs of sarin poisoning, including foaming at the mouth, breathing difficulties and limp bodies, following the Tuesday attack.

Moments after the Tuesday attack a projectile hit a hospital in the area, bringing down rubble on top of medics as they struggled to treat victims.

The death toll is likely to rise, according to the Union of Medical Care Organizations, a coalition of international aid agencies that funds hospitals in Syria and which is partly based in Paris.

The Syrian Observatory for Human Rights said those killed had died from suffocation and the effects of the gas. The monitor could not confirm the nature of the gas, and said the strike was likely carried out by government warplanes.

A senior Syrian security source claims that allegations that Syria's government killed dozens of civilians on Tuesday in a chemical attack on a northwestern rebel-held town are 'false'.

'This is a false accusation,' the source said, adding that opposition forces were attempting to 'achieve in the media what they could not achieve on the ground'.

Many victims, including children, were stripped down to their underwear and sprayed with hoses as activists tried to wash the gas off of them. Pictured above, a Syrian child receives treatment following the attack

The death toll is likely to rise, according to the Union of Medical Care Organizations, a coalition of international aid agencies that funds hospitals in Syria and which is partly based in Paris. Pictured above, Syrian children receive treatment following the suspected toxic gas attack in Khan Sheikhun on Tuesday

Syrian doctors treat a child following a suspected chemical attack, at a makeshift hospital, in the town of Khan Sheikhoun

Some victims were foaming at the mouth following the toxin attack - a symptom of the poison sarin, which is used as a chemical weapon

Local reports quoted doctors saying the chemical that killed dozens of people in the region could have been chlorine or sarin, a colorless, odorless liquid nerve agent that's used as a chemical weapon.

Chlorine attacks are used quite often in Syira, to kill small groups of people in enclosed spaces where gas dissipates quickly, according to the New York Times.

But Tuesday's attack was different: people collapsed outdoors, in large numbers and suffered different symptoms.

Victims foamed at the mouth and had pinpoint pupils - a side effect that happens when people come into contact with nerve agents and other banned toxins.

A Syrian military source denied that government forces used any such weapons, saying the army 'does not and has not' used chemical weapons 'not in the past and not in the future'.

A series of investigations by the United Nations and the Organisation for the Prohibition of Chemical Weapons (OPCW) found that various parties in the Syrian war have used chlorine, sulfur mustard gas and sarin.

Still, Damascus has repeatedly denied using chemical weapons.

Victims suffered from fainting, vomiting, foaming at the mouth and pinpoint pupils, medical sources told local reports.

Activists in northern Syria circulated pictures on social media showing a reported victim with foam around his mouth, and rescue workers hosing down almost naked children squirming on the floor.

The activist-run Assi Press published video of paramedics carrying victims from the scene by a pickup truck. The victims were stripped down to their underwear. Many appeared unresponsive.

Syrian activists said that makeshift hospitals soon crowded with people suffocating from toxins following the attack.

A medical doctor going by the name of Dr Shajul Islam on Twitter said his hospital in Idlib province received three victims, all with narrow, pinpoint pupils that did not respond to light.

He published video of the patients on his Twitter account.

An unconscious Syrian child is carried at a hospital in Khan Sheikhun, a rebel-held town in the northwestern Syrian Idlib province, following the gas attack

Many patients had to receive help breathing following the attack, as one of the several symptoms of sarin is having trouble breathing

A boy covers his face with his hands as doctors evaluate wounds to his legs and feet following the toxin attack on Tuesday

An unconscious Syrian child is carried at a hospital in Khan Sheikhun, a rebel-held town in the northwestern Syrian Idlib province

A man gets treatment at a hospital after Assad Regime forces released a suspected toxic gas on to Khan Shaykhun

Sarin, which is made by combining the fluorine in sodium fluoride with carbon, hydrogen, oxygen and phosphorous, is considered one of the world's most dangerous chemical warfare agents. Pictured above, a Syrian man receives treatment after an alleged chemical attack at a field hospital in Saraqib, Idlib

Pinpoint pupils, breathing difficulties, and foaming at the mouth are symptoms commonly associated with toxic gas exposure.

'Our hospital getting full from sarin attack today,' he wrote of his hospital in Hama, which is a short drive away from Khan Sheikhoun. 'Anyone that wants evidence, I will video call you.'

Islam, who trained in the UK and now works in northern Syria, said that seriously ill patients were still 'flooding' into his hospital.

'The patients keep just flooding in from this chemical attack,' he says in a Twitter video , purportedly taken inside a Syrian hospital this morning. 'Every one - every one - has got pinpoint pupils'.

'The patients keep coming, we've run out of ventilators,' the humanitarian aid added.

'We don't have enough ventilator space, so we're now taking out the transport ventilators we have in our ambulances and we're going to try to modify them to see if we can use them for our patients.'

HOW PRESIDENT ASSAD HAS USED CHEMICAL WEAPONS ON HIS OWN PEOPLE Syria has a long history with chemical weapons dating back more than 40 years. Syria first developed chemical weapons in the 1970s, when it was given a small number of chemicals and delivery systems by Egypt before the start of the Arab-Israeli war in 1973. Damascus started acquiring materials to produce its own chemical weapons in the 1980s, reportedly with the help of the Soviet Union, according to the BBC. By 2011, Syria was still 'dependent on foreign sources of key elements' of its chemical weapons, the US director of national intelligence reported. In 2013, the country saw its worst sarin attack in Syria's civil war. In the wake of the 2013 attack, President Bashar Assad agreed to a Russia-sponsored deal to destroy his chemical arsenal and joined the Chemical Weapons Convention. The agreement came after hundreds of people - up to 1,429 according to a US intelligence report - were killed in chemical weapons strikes allegedly carried out by Syrian troops east and southwest of Damascus. His government declared a 1,300-ton stockpile of chemical weapons and so-called precursor chemicals that can be used to make weapons amid international outrage at a nerve gas attack on the outskirts of Damascus. Those weapons have been destroyed, but member states of the OPCW have repeatedly questioned whether Assad declared everything in 2013. The widely available chemical chlorine was not covered in the 2013 declaration and activists say they have documented dozens of cases of chlorine gas attacks since then. The Syrian government has consistently denied using chemical weapons and chlorine gas, accusing the rebels of deploying it in the war instead. But there have been repeated allegations of chemical weapons use by the government since then, with a UN-led investigation pointing the finger at the regime for at least three chlorine attacks in 2014 and 2015. The government denies using chemical weapons and has accused rebels of using banned weapons. Advertisement

Islam said that it was 'definitely not a chlorine attack', suggesting that the more severe sarin was used.

Footage from his hospital shows adults and children lying on hospital beds unresponsive, as medics work to save their lives.

'I will show you the evidence again and again, but you know what? The world doesn't care and no-one is doing anything,' says Dr Islam. 'We urge you to put pressure on your government - put pressure on anyone - to help us.'

Mohammed Hassoun, a media activist in nearby Sarmin - also in Idlib province where some of the critical cases were transferred - said the hospital there had been equipped to deal with such chemical attacks because the town was struck in one chemical attack, early on in the Syrian uprising.

The wounded have been 'distributed around in rural Idlib', he told The Associated Press by phone.

'There are 18 critical cases here. They were unconscious, they had seizures and when oxygen was administered, they bled from the nose and mouth,' he added.

Hassoun, who is documenting the attack for the medical society, said the doctors there have said it is likely more than one gas. 'Chlorine gas doesn't cause such convulsions,' he said, adding that doctors suspect sarin was used.

An AFP journalist in Khan Sheikhun saw a young girl, a woman and two elderly people dead at a hospital, with foam still visible around their mouths.

Doctors at the facility were using basic equipment, some not even wearing lab coats, and attempting to revive patients who were not breathing.

A father carried his dead little girl, her lips blueish and her dark curls visible, wrapped in a blue sheet.

As doctors worked, a warplane circled overhead, striking first near the facility and then hitting it twice, bringing rubble down on medics and patients.

The province of Idlib is almost entirely controlled by the Syrian opposition and is largely controlled by an alliance of rebels including former Al-Qaeda affiliate Fateh al-Sham Front.

It is regularly targeted in strikes by the regime, as well as Russian warplanes, and has also been hit by the US-led coalition fighting the Islamic State group, usually targeting jihadists.

But the province is home to some 900,000 displaced Syrians, according to the United Nations.

Local reports quoted doctors saying the chemical that killed dozens of people in the region could have been chlorine or sarin, a colorless, odorless liquid nerve agent that's used as a chemical weapon

Victims suffered from fainting, vomiting, foaming at the mouth and pin-point pupils, medical sources told local reports. Pictured above, a Syrian man receives treatment following the gas attack

Mohammed Hassoun, a media activist in nearby Sarmin - also in Idlib province where some of the critical cases were transferred - said the hospital there had been equipped to deal with such chemical attacks because the town was struck in one chemical attack, early on in the Syrian uprising Syrian activists said that makeshift hospitals soon crowded with people suffocating from toxins following the attack

Idlib province is largely controlled by an alliance of rebels including former Al-Qaeda affiliate Fateh al-Sham Front. Civil defense members tried to reduce the effects of chlorine gas with water as they carried out search and rescue works after a suspected chlorine gas attack in Idlib, Syria

Moments after the attack a projectile hit a hospital in the area, bringing down rubble on top of medics as they struggled to treat victims

DOCTOR TELLS OF HORRORS AFTER TOXIN ATTACK A medical doctor going by the name of Dr. Shajul Islam on Twitter said his hospital in Idlib province received three victims, all with narrow, pinpoint pupils that did not respond to light. He published video of the patients on his Twitter account. Pinpoint pupils, breathing difficulties, and foaming at the mouth are symptoms commonly associated with toxic gas exposure. 'Our hospital getting full from sarin attack today,' he wrote of his hospital in Hama, which is a short drive away from Khan Sheikhoun. 'Anyone that wants evidence, I will video call you.' Dr Islam, who trained in the UK and now works in northern Syria, said that seriously ill patients were still 'flooding' into his hospital. A medical doctor going by the name of Dr. Shajul Islam on Twitter said his hospital in Idlib province received three victims, all with narrow, pinpoint pupils that did not respond to light Dr Islam said that his hospital in Hama, which is a short drive away from Khan Sheikhoun, received several victims of a suspected sarin attack 'The patients keep just flooding in from this chemical attack,' he says in a Twitter video , purportedly taken inside a Syrian hospital this morning. 'Every one - every one - has got pinpoint pupils'. 'The patients keep coming, we've run out of ventilators,' the humanitarian aid added. 'We don't have enough ventilator space, so we're now taking out the transport ventilators we have in our ambulances and we're going to try to modify them to see if we can use them for our patients.' Dr Islam said that it was 'definitely not a chlorine attack', suggesting that the more severe sarin was used. Footage from his hospital shows adults and children lying on hospital beds unresponsive, as medics work to save their lives. 'I will show you the evidence again and again, but you know what? The world doesn't care and no-one is doing anything,' says Dr Islam. 'We urge you to put pressure on your government - put pressure on anyone - to help us.' Dr Islam said that it was 'definitely not a chlorine attack', suggesting that the more severe sarin was used. Footage from his hospital shows adults and children lying on hospital beds unresponsive, as medics work to save their lives. Doctors at the facility were using basic equipment, and attempting to revive patients who were not breathing following the attack An AFP journalist in Khan Sheikhun saw a young girl, a woman and two elderly people dead at a hospital, with foam still visible around their mouths. Doctors at the facility were using basic equipment, some not even wearing lab coats, and attempting to revive patients who were not breathing. A father carried his dead little girl, her lips blueish and her dark curls visible, wrapped in a blue sheet. As doctors worked, a warplane circled overhead, striking first near the facility and then hitting it twice, bringing rubble down on medics and patients. In a video posted online by Idlib's local medical directorate, a doctor described patient symptoms as he treated a child. 'We are seeing unconsciousness, convulsions, pinpoint pupils, severe foaming, and lack of oxygen,' he said. Dr Islam, who trained in the UK and now works in northern Syria, said that seriously ill patients were still 'flooding' into his hospital Advertisement

The reports came on the eve of a major international meeting in Brussels on the future of Syria and the region hosted by the EU's High Representative, Federica Mogherini.

Claims of chemical weapons attacks, particularly the use of the chlorine agent, are not uncommon in Syria's conflict.

The worst attack was what a UN report said was an attack by toxic sarin gas in August 2013 on the Damascus suburb of Ghouta that killed hundreds of civilians.

HOW SARIN AND CHLORINE ARE USED IN CHEMICAL AND TOXIC GAS ATTACKS SARIN Sarin, which is made by combining the fluorine in sodium fluoride with carbon, hydrogen, oxygen and phosphorous, is considered one of the world's most dangerous chemical warfare agents. It disrupts the nervous system, over-stimulating muscles and vital organs. It is more than 500 times as toxic as cyanide. It can be inhaled as a gas or absorbed through the skin. In high doses, sarin suffocates its victims by paralysing the muscles around their lungs, and one drop can kill in minutes. CHLORINE Chlorine is a toxic industrial gas that irritates the throat can cause victim's lungs to fill with water, drowning them. The gas can also attack the skin and eyes, causing burning, swelling, itching and irritation. The first large-scale use of chlorine as a weapon, at Ieper, Belgium, on April 22, 1915, unleashed massive use of gas by both Germany and the Allies during the last three years of the 1914-1918 war. Chemical weapons killed nearly 100,000 and injured around 1 million more during the conflict. The horrific scale of World War I gas casualties — and the suffering they caused — helped launch what has been hailed as one of the most successful disarmament campaigns in history. It culminated in the 1997 Chemical Weapons Convention and creation of the Hague-based Organization for the Prohibition of Chemical Weapons. The watchdog with 190 member states won the Nobel Peace Prize in 2013. Advertisement

Rebels and opposition officials have expressed concerns that the government is planning to mount a concentrated attack on the crowded province.

The Syrian Coalition, an opposition group based outside the country, said government planes fired missiles carrying poisonous gases on Khan Sheikhoun, describing the attack as a 'horrifying massacre'.

Syria's government officially joined the Chemical Weapons Convention and turned over its chemical arsenal in 2013, as part of a deal to avert US military action.

But there have been repeated allegations of chemical weapons use by the government since then, with a UN-led investigation pointing the finger at the regime for at least three chlorine attacks in 2014 and 2015.

The government denies the use of chemical weapons and has in turn accused rebels of using banned weapons.

Tuesday's attack comes only days after forces loyal to Assad were accused of using chemical weapons in a counter-offensive in neighbouring Hama province.

Syria's opposition National Coalition accused Assad's government of a suspected toxic, and demanded a UN investigation.

'The National Coalition demands the Security Council convene an emergency session..., open an immediate investigation and take the necessary measures to ensure the officials, perpetrators and supporters are held accountable,' the body said in a statement.

Syrian and Russian air strikes have battered parts of Idlib, according to the Observatory, despite a ceasefire that Turkey and Russia brokered in December.

Jets also struck the town of Salqin in the north of Idlib province on Tuesday, killing eight people, the monitor said.

If confirmed, it would be one of the worst chemical attacks since the start of Syria's civil war six years ago.

An international chemical weapons watchdog says it is gathering and analyzing information about the suspected chemical attack.

The Organization for the Prohibition of Chemical Weapons says its Fact Finding Mission 'is in the process of gathering and analyzing information from all available sources.'

A civil defence member breathes through an oxygen mask, after what rescue workers described as a suspected gas attack in the town of Khan Sheikhoun

A man breathes through an oxygen mask, after what rescue workers described as a suspected gas attack in the town of Khan Sheikhoun

A Syrian doctor helped a boy following the suspected attack, which has been described as one of the worst in the country's six-year civil war

Idlib is regularly targeted in strikes by the regime, as well as Russian warplanes, and has also been hit by the US-led coalition fighting the Islamic State group, usually targeting jihadists. pictured above, a victim of a suspected chemical attack as he receives treatment at a makeshift hospital

A Syrian man is taken by civil defence workers to a small hospital in the town of Maaret al-Noman following the suspected sarin attack

People stand near a dead body, after what rescue workers described as a suspected gas attack in the town of Khan Sheikhoun in rebel-held Idlib, Syria

The mission will report its findings to the OPCW's executive council. Syria joined the organization in 2013.

The organization, which won the 2013 Nobel Peace Prize for its chemical disarmament efforts, says it 'strongly condemns the use of chemical weapons by anyone, anywhere and under any circumstances.'

More than 320,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests.

Tuesday's gathering in Brussels was been billed as a follow-up to a donors' conference last year in London, which raised about $11 billion for humanitarian aid programs in the devastated country.