A The New York Times expose revealed cache of weapons were found between 2004 and 2011. Most of them were mustard agents in 155-millimeter artillery shells or 122-millimeter rockets.

Had been developed by Saddam Hussein in the 1980s but abandoned
At least 17 American military personnel were injured
Pentagon chose not to release the information to the public
The weapons did not meet George W. Bush's rationale that Hussein had a program of 'mass destruction'

Aboout 5,000 chemical weapons were recovered or destroyed in Iraq following the 9/11 invasion but the Pentagon chose to keep the findings a secret, it has emerged.

A major investigation by The New York Times has revealed that U.S. forces happened across hidden caches of warheads, shells and aviation bombs between 2004 and 2011 that had been sitting dormant since the early 1980s.

The dangerous weapons - most of them mustard agents in 155-millimeter artillery shells or 122-millimeter rockets - were developed by Saddam Hussein during the Iran-Iraq war, with hundreds of tons of chemicals created at any one time.

Between 2004 and 2011, according to the Times, soldiers found thousands of rusty chemical munitions throughout Iraq, most of them buried.

Documenting chemical weapons added hours of extra work.

Chemical warfare specialists had to be called in, and waiting for them to arrive put coalition in precarious positions.
It also stopped them from destructing other explosives that were killing people every week.

'I could wait all day for tech escort to show up and make a chem round disappear, or I could just make it disappear myself,' one told The Times.

The mustard shells could be put in with other explosives that needed to be destructed and then detonated.

However, handling chemical weapons lead to many injuries, which were not taken seriously by military doctors at the time.

At least 17 American military personnel and seven Iraqi police were sickened by poisons - usually sarin and mustard gases - since 2003.

Many of the shells would leak liquid during transportation, exposing the soldiers to the potentially-lethal fumes.

Symptoms would range from disorientation and nausea to blindness and huge, seething blisters.

Jarrod L. Taylor, a former Army sergeant on hand for the destruction of mustard shells that burned two soldiers in his infantry company, joked of 'wounds that never happened' from 'that stuff that didn’t exist'.

'I love it when I hear, ‘'Oh there weren't any chemical weapons in Iraq'',’ he said.

'There were plenty.'

The New York Times published the expose on Tuesday night.

The report was written by C. J. CHIVERS.