I'm not sure. The first time I heard the term "Pax Americana" was yesterday on CSPAN from an Anti-War 'spokesperson' who spoke after a Jewish protester read his poem titled "Who Be Frontin'?"
I am not fully sure where the term "PAX Americana" came from. In hearing discussions, and reading comments it seems to be a representation of the policy of retaining American superiority as a super power, using a policy of maintaining a pre-emptive stance. Here is a link to a Yahoo Search of the term:
http://search.yahoo.com/search?p=PAX+Americana
The Defense Department's current strategy seems to contain many of the concepts presented in the PNAC document; a 90 page document footnoted to support the 76 pages of the actiual text. Here is the list of participants, and the descriptor of what constituted participation.
Roger Barnett
U.S. Naval War College
Alvin Bernstein
National Defense University
Stephen Cambone
National Defense University
Eliot Cohen
Nitze School of Advanced International
Studies, Johns Hopkins University
Devon Gaffney Cross
Donors' Forum for International Affairs
Thomas Donnelly
Project for the New American Century
David Epstein
Office of Secretary of Defense,
Net Assessment
David Fautua
Lt. Col., U.S. Army
Dan Goure
Center for Strategic and International Studies
Donald Kagan
Yale University
Fred Kagan
U. S. Military Academy at West Point
Robert Kagan
Carnegie Endowment for International Peace
Robert Killebrew
Col., USA (Ret.)
William Kristol
The Weekly Standard
Mark Lagon
Senate Foreign Relations Committee
James Lasswell
GAMA Corporation
I. Lewis Libby
Dechert Price & Rhoads
Robert Martinage
Center for Strategic and Budgetary
Assessment
Phil Meilinger
U.S. Naval War College
Mackubin Owens
U.S. Naval War College
Steve Rosen
Harvard University
Gary Schmitt
Project for the New American Century
Abram Shulsky
The RAND Corporation
Michael Vickers
Center for Strategic and Budgetary
Assessment
Barry Watts
Northrop Grumman Corporation
Paul Wolfowitz
Nitze School of Advanced International
Studies, Johns Hopkins University
Dov Zakheim
System Planning Corporation
The above list of individuals participated in at least one project meeting or contributed a paper for discussion. The report is a product solely of the Project for the New American Century and does not necessarily represent the views of the project participants or their affiliated institutions.
Here is the P.N.A.C. Site
The Project for a New American Century
This project is apparently what inspired the concept known as PAX AMericana
http://www.newamericancentury.org/
The current Defense Department strategy is contained in a 31 page publication entitled National Security Strategy of the United States, and was released September 2002.
Here is a great resource for DOD info:
http://www.defenselink.mil/pubs/
Here is the link to the actual DOD National Security Strategy in .html format:
http://www.whitehouse.gov/nsc/nssall.html
Here is the link for the nss.pdf file. it will start the .pdf file download. If there is a way for you to left click it without redirection, you will have the opportunity to save the file for later reference.
http://www.whitehouse.gov/nsc/nss.pdf
PAX Americana, the PNAC and the NSS document have been used against the administration to support the dovish reaction to what is perceived to be a hawkish administration. I hope the trail I have provided here will portray the linkage I perceive to tie the documents together. I view the project and resulting NSS document with mixed emotions. I am for action in Iraq as a necessary evil, and agree that the liberation of the Iraqi people is admirable. However, I feel the bigger purpose of the action is to stop the EU from using ME oil producers to destruct the US Dollar through their campaign to have OPEC only accept payment for oil in Euros. At any rate, we have already defeated France and the EU by going outside the UN, which as apparently biased toward the EU's cause.
These may be weak linkages that I have provided. It is the best history I can provide for the evolution of ideas that I feel link the Letter to Clinton to the current Defense Strategy.