If you would like a concrete instance of zero credibility of the U.S., I suggest you read this detailed account of how the U.S. dealt with Iran on one proposal and on how it sandbagged Turkey and Brazil.
3:40 pm CDT
February 2, 2012
http://www.lewrockwell.com/lrc-blog/u-s-negotiating-duplicity/
If you would like a concrete instance of zero credibility of the U.S., I suggest you read this detailed account of how the U.S. dealt with Iran on one proposal and on how it sandbagged Turkey and Brazil.