If Rio leaves Alaska/Pebble, it may not be because of pressures from enviro-Nazi's. Development and exploration projects around the globe are suffering startigic realignments in the current environment, as this story clearly illustrates.
http://www.fool.com/investing/general/2013/12/16/this-massive-copper-project-still-wont-see-the-lig.aspx#.UrXB7_uzavB
So, it well could be that the anit-Pebble crowd happen to have coincidental economic conditions working on their behalf for the time being. I like this explanation better than having to accept the fact that they are powerful enough to push around a couple of the world's largest mining companies.
VP
[Looking for voters to take a sharp turn to the Right in the coming election cycles.]