It is about timing. For example, if you retain cash in $A...

It is about timing. For example, if you retain cash in $A (repatriated $US iron ore sales) after sales and the currency subsequently moves against you, your debt position will have increased. Not so if you pay the debt down immediately.

This is only one example...but the currency impact is important.

The $A is expected to go down over time as the US economy recovers and eventually lifts interest rates to more traditional settings. This would have a positive effect on sales for those earning in $US (as exporters of iron ore do) but will also have a corresponding negative effect if debt is in $US.