MSNBC host Lawrence O'Donnell has come under fire for promoting a conspiracy theory that suggests Vladimir Putin orchestrated the Syrian chemical attack as a way to help Donald Trump's image.

A number of theories started flowing soon after US missiles were fired at a Syrian airbase on Thursday night about the real reason behind the international crisis.

O'Donnell opted to run with one of the conspiracy theories and dedicated considerable airtime to it during his The Last Word program on Friday night.

Scroll down for video

MSNBC host Lawrence O'Donnell has come under fire for promoting a conspiracy theory that suggests Putin orchestrated the Syrian chemical attack as a way to help Trump's image

He argued that it was conceivable to suggest that Putin ordered Bashar al-Assad to carry out the chemical attack in Syria and prompt Trump to fire missiles in retaliation as a way to distract Americans from an investigation into the US president's campaign ties to Russia.

O'Donnell, who didn't offer any evidence to support his theory, suggested that the impossible scenario was now possible given Trump's credibility problems.

He said it was conceivable Putin had ordered the chemical attack knowing that 'his friend in the White House' would see it on TV and fire missiles at Syria 'that will do no real damage'.

'Then American news media will change the subject from Russian influence in the Trump campaign and the Trump transition and the Trump White House. It's perfect,' O'Donnell said.

'It doesn't just change the subject. It changes the conventional wisdom about the dynamic between Vladimir Putin and Donald Trump. President Trump has finally dared to do something Vladimir Putin doesn't like. It changes everything... as long as you never question whether Vladimir Putin wanted all of this to happen.'

O'Donnell suggested Vladimir Putin orchestrated the chemical gas attack to help Trump's image and deflect from the investigation into Russian influence in the US election

O'Donnell didn't offer any evidence to support his theory but said Donald Trump has shown that anything is possible since he became president

O'Donnell said not one word of the theory could have been said about a previous US president and blamed the situation on the 'world Donald Trump has given us'.

'Don't you miss those days that if there was a chemical attack in Syria you could be absolutely sure that President Assad and President Putin did not do that in order to help the image of the President of the United States?

'What you won't hear is proof that the scenario I've just outlined is impossible because what the presidency of Donald Trump has shown is that anything is possible.'

Reaction to O'Donnell's theory was swift with some on Twitter calling him 'deranged'.

'You don't know what fake news is until you watch Lawrence O'Donnell talk about Syria,' one Twitter user wrote.

Another said: 'MSNBC'S Lawrence O'Donnell is so paranoid that he thinks Putin and Trump worked together to gas civilians in Syria. He's unhinged.'

O'Donnell had previously claimed on Wednesday night's show that Trump's administration essentially said the president was 'okay' with Assad using chemical weapons on civilians.

'Men, women, children, and babies got gassed in Syria this week because last week, the Trump administration gave the signal that that was OK with President Trump,' O'Donnell said.

Secretary of state Rex Tillerson said at a press conference last week that Assad's future in Syria would be determined by the Syrian people.

O'Donnell lashed out saying the comment was 'the most dangerous and irresponsible thing that he could have said given the state of the world today.'

He added that Tillerson was 'the most untrained and inept secretary of state in modern history.'