On 1 June 2012 Defense.gov published an item: AFGHANISTAN: A combined patrol discovered a weapons cache containing three shoulder-fired, surface-to-air missiles, three anti-tank mines, 423 RPGs, 118,600 7.62 mm rounds, 30 rifles and other ordnance in the Tarin Kot district of Uruzgan province. The cache’s contents were destroyed.” No mention of the origin of these weapons was made. Unfortunately this item is no longer available on Defense.gov. The link informs the reader, “Defense.gov has recently migrated to a new hosting platform. As a result, many URLs have changed.” The origin of these missing 400 missiles is significant.
Your quote says three SAM’s and 423 RPG’s.