As I've heard, there's a significant financial penalty against the airlines by foreign governments if a pax is delivered without proper docs (and has to be returned home), hence the efficiency at not letting someone on an international segment without a D/A. If this were a single itinerary, single-PNR, MSP-LAX-AMS-LAX-MSP, and there was no D/A at MSP-LAX, it appears to be a breakdown in process by NW in MSP.

Appears LAX-AMS-LAX is the KL601/KL602 turn (and 747!). Could the international segment of a PNR being on a codeshare have prevented the D/A requirement at initial departure?

Steve B.