Soldiers in Afghanistan (Creative Commons)

The program was supposed to prevent insurgents from planting bombs by covering culverts with metal grates. Thousands were supposed to have been installed since 2009, but investigators found that hundreds were not installed, reports the NY Times.

The report blames an Afghan contractor and his subcontractor. The two have been charged with negligent homicide and fraud.

One of the men is in custody in this case, which marks the first time Afghan contractors have been directly linked to American deaths.

Investigators have already found one case in which missing or faulty grates resulted in casualties.

Reach Executive Producer Hannah Madans here.