Rio Tinto may have lost the battle in 1990 but, if the Bougainville Mining Bill is passed, they have won the war.
The key section announcing the coup is buried right at the end of the Bill. If passed, Rio Tinto's special mining lease will be converted into an exploration licence, which can then in turn be re-converted into a mining lease under the law.
Why is this a coup? Surely this is a loss for Rio Tinto? Well ...