And when did they know it?

Military leaders knew the dangers posed by roadside bombs before the start of the Iraq war but did little to develop vehicles that were known to better protect forces from what proved to be the conflict’s deadliest weapon, a report by the Pentagon inspector general says.

The Pentagon “was aware of the threat posed by mines and improvised explosive devices (IEDs) … and of the availability of mine resistant vehicles years before insurgent actions began in Iraq in 2003,” says the 72-page report, which was reviewed by USA TODAY.

The report is to be made public today.

Marine Corps leaders “stopped processing” an urgent request in February 2005 for Mine Resistant Ambush Protected (MRAP) vehicles from combat commanders in Iraq’s Anbar province after declaring that a more heavily armored version of existing Humvee vehicles was the “best available” option for protecting troops, the report says.

When field commanders first began requesting MRAPs, military officials saw the armored Humvees as a more immediate option to countering IEDs, Pentagon press secretary Geoff Morrell said. “The threat has evolved and our force protection measures have evolved with it,” he said.

The Marines requested the inspector general’s investigation in February after an internal report accused the Corps of “gross mismanagement” of the urgent request for MRAPs. Hundreds of Marines died unnecessarily because of delays in fielding the vehicles, said the Jan. 22 study by Franz Gayl, a retired Marine officer and civilian science adviser.