Defence Secretary Donald Rumsfeld was blunt in his advice to...

Defence Secretary Donald Rumsfeld was blunt in his advice to Turkey at a Pentagon briefing.

"We have special forces units connected to Kurdish forces in the north ... and you can be certain that we have advised the Turkish government and the Turkish armed forces that it would be notably unhelpful if they went into the north in large numbers."

The dangers are clear for Washington if its troops drive up into the north, where important oil fields are located, and are confronted with Turkish forces outside coalition command.

But it's not about oil.