US soldiers have deep concerns about the force, and say that its members collude with insurgents.
But only 200 officers in the south have been trained so far in a US-led program to stem trafficking in and out of Pakistan.
Defense officials say it will fill urgent gaps but Special Forces officers are skeptical.
Some tribes have forced insurgents from their area, but many risks remain.
The case against Aafia Siddiqui, who has been missing since 2003, raises questions about illegal detention centers across Pakistan.
Deployment of 3,200 marines will help, analysts say, but will not provide the kind of counterinsurgency now needed there.