US television drama The Newsroom echoed events in the real world with its recent sarin gas attack storyline.

But in the show it's not the Syrian government that is accused of using chemical weapons but the US government itself.

Penned by West Wing writer Aaron Sorkin, the series is set behind the scenes at the fictional Atlantis Cable News (ACN), centring around the exploits of anchorman Will McAvoy.

Led by McAvoy, the news team believe they have uncovered a massive cover-up by the US military.

During the discussions about whether to run the story, white phosphorus is mentioned, with ACN's president Charlie Skinner noting in passing that if US forces "shot white phosphorus into an enclosed area that alone would be chemical warfare." His remark is ignored and the narrative soon moves on.

Sorkin, seen as one of the most intelligent writers working in television, seems to be unaware that there is no need to explore the issue in a fictional context.

The US has fired white phosphorus in an enclosed area - in Fallujah, Iraq, in 2004, with many arguing this constituted the use of a chemical weapon.

It's hard to come by reliable figures on how many Iraqis were killed by white phosphorus in Fallujah. However a Red Cross official noted that overall at least 800 civilians were killed during the November 2004 assault on the city.

During the attack the US targeted medical buildings, cut off the water and electricity supply, refused entry to aid agencies and refused exit from the battle zone to men aged 15 to 55 years old.

Initially, when questions were raised, the US military denied using white phosphorus as a weapon.

However in 2005 bloggers uncovered evidence indicating the US had indeed done just that.

They found an edition of the US army's Field Artillery magazine of that year which admitted that "WP proved to be an effective and versatile munition," in the Fallujah attack.

"We used it for screening missions at two breaches and, later in the fight, as a potent psychological weapon against the insurgents in trench lines and spider holes where we could not get effects on them with HE [high explosive].

"We fired 'shake and bake' missions at the insurgents, using WP to flush them out and HE to take them out."

Speaking to the BBC, a spokesman for the Organisation for the Prohibition of Chemical Weapons (OPCW) stated that if "the toxic properties of white phosphorus, the caustic properties, are specifically intended to be used as a weapon, that of course is prohibited because the way the [Chemical Weapons] Convention is structured, or the way it is in fact applied, any chemicals used against humans or animals that cause harm or death through the toxic properties of the chemical are considered chemical weapons."

Most lay people would agree that this quote seems to show US use of white phosphorus falls within this definition.

The Guardian columnist George Monbiot agrees, telling Democracy Now! in 2005: "The US army was acting in direct contravention of the Chemical Weapons Convention. It committed a war crime."

However the chemical weapons experts I contacted for clarification were far from certain.

Dan Kaszeta, a former officer in the US army's chemical corps, said: "WP falls into a grey area" and opinions vary widely.

Alastair Hay, a professor of environmental toxicology at the University of Leeds, noted that the OPCW definition "requires a lawyer to interpret it."

Another expert, who declined to be quoted, explained that if used as an incendiary WP is not a chemical weapon, although if it is used for its toxic properties then it could be considered a chemical weapon.

While the experts stress the complexity of the issue, it should be noted the Pentagon has no problem making a clear statement on the subject.

A declassified US Department of Defence document from 1991 reports that "Iraqi forces loyal to president Saddam may have possibly used white phosphorus (WP) chemical weapons against Kurdish rebels."

All this is important when one considers how the possible use of chemical weapons by the Syrian government in August 2013 caused an avalanche of moral outrage in the media.

Taking her cue from the US and British governments, the day after the chemical weapons attack Channel 4 News's Sarah Smith asked: "Syria chemical weapons horror - is it time for intervention?"

Over at the Independent, the front page headline on August 26 2013 was "Syria: air attacks loom as West finally acts."

The Indy's use of "finally" speaks volumes.

Compare this with the mainstream media's desultory coverage of Fallujah - and even this was largely following pressure from concerned viewers and readers.

There was, and continues to be, a noticeable lack of moral outrage outside of a couple of honourable exceptions like Monbiot and John Pilger.

And there has been a distinct lack of further journalistic investigation, which if the experts' uncertainty is anything to go by, is desperately needed to uncover the truth.

Sorkin, along with many contemporary conspiracy theorists, seems to misunderstand how modern-day propaganda works.

The most effective, most insidious thought control is not based on huge cover-ups involving tens, maybe hundreds of people.

After all the US use of white phosphorus in 2004 did receive some coverage in the mainstream media.

More importantly it was quickly forgotten, and it certainly didn't inform the political debate about how or who should to respond to the Syrian government's possible use of chemical weapons.

War crimes happen and war criminals get away with it because the historical events are refracted and therefore shaped by non-conspiratorial journalistic and academic processes such as omission of key facts, framing, sourcing bias, subservience to power, careerism and adherence to the dominant ideology.

As with many things, George Orwell explained it best.

"The sinister fact about literary censorship in England is that it is largely voluntary," he wrote in the suppressed preface to his 1945 classic novella Animal Farm.

"Unpopular ideas can be silenced, and inconvenient facts kept dark, without the need for any official ban."

How? "At any given moment there is an orthodoxy, a body of ideas which it is assumed that all right-thinking people will accept without question. It is not exactly forbidden to say this, that or the other, but it is 'not done' to say it."

The continued silence of the vast majority of British journalists, columnists and editors clearly shows it is currently "not done" to say the US may well have used chemical weapons in Fallujah. Or that the US helped Iraq to use nerve gas during the Iran-Iraq war, as Foreign Policy magazine recently reported.

No doubt many journalists in Syria have also stayed silent about the many crimes of the Assad government. And for good reason - reporting inconvenient truths in Syria today could well be life-threatening.

What excuse do journalists working in our supposedly free and combative media have for their silence?

Ian Sinclair is the author of The March That Shook Blair: An Oral History Of 15 February 2003, published by Peace News Press. You can follow him on Twitter at twitter.com/IanJSinclair.