In 1969 , 433,000 tonnes of ordnance fell on Laos .
As many as 43,000 North Vietnamese or Laotians ( most of whom were pressed into service ) were engaged in operating , improving , or extending the system .
In 1969 , 433,000 tonnes of ordnance fell on Laotians .
As many as 43,000 North Vietnamese or Laotians ( most of whom were pressed into service ) were engaged in operating , improving , or extending the system .