What is it?
Combined action is a deliberate task organization that partners and embeds U.S. forces training teams with a host nation unit to conduct operations with a host nation face. U.S. forces can show host nation forces what right looks like, hold the host nation forces accountable for their actions, and are less likely to offend the host nation populace. The end state of combined action is the local populace having trust and confidence in local security forces. U.S. forces do not withdraw from being embedded; instead they gradually thin out and maintain a headquarters as there is a reduction of combat forces.
What has the Army done?
First coined during Vietnam, combined action is executed in a similar manner: Small teams living amid the populace, partnering with local forces to drive a wedge between the populace and the insurgency. The Army started combined action in both Iraq and Afghanistan and sees improvements in both Iraqi Security Forces (ISF) and Afghan National Security Forces (ANSF). Combined action operations are taking place now in the Khost-Gardez pass. ANSF and Coalition forces are partnering there to improve security and governance.
What continued efforts does the Army have planned for the future?
The Army continues to use and refine this model. As host nation security forces conduct operations with confidence and integrity, the populace can begin to trust in these forces. The Iowa National Guard 2-34th IBCT (Red Bulls) is training on current patrol techniques, key leader engagements, and partnering with local security forces in the current contemporary operating environment for this mission.
Why is this important to the Army?
Combined action is paramount to defeating insurgency. Through combined action the Army, working in conjunction with ANSF, can restore the trust and confidence that the local populace has toward its local security forces.
STAND-TO! Resources:
COMISAF's Counterinsurgency Guidance - General David Petraeus
Combined Action in Afghanistan; August 2010 - Company Command document
Combined Action in the Khost-Gardez Pass - Related article
Small Wars Journal Resources (USMC / Vietnam):
Did the Marines Better Understand the Nature of the Vietnam Conflict and Was the Combined Action Program More Suitable than Civil Operations Revolutionary Development Support in Dealing With Insurgents? - Major Kenneth Eugene Wynn
Combine Action and US Marine Experiences in Vietnam, 1965-71 - Major Phillip Ridderhof
Combined Action Platoons: A Strategy for Peace Enforcement - Major Brooks Brewington
The U.S. Marine Corps Combined Action Program (CAP): A Proposed Alternative Strategy for the Vietnam War - Major Curtis Williamson III
Civic Action: The Marine Corps Experience in Vietnam - Peter Brush
The Combined Action Program: Vietnam - Captain Keith Kopets
Insurgency, Counterinsurgency, And The Marines In Vietnam - Major Frank Pelli
The Marine Corps' Combined Action Program and Modern Peace Operations - Common Themes and Lessons - Major William Go
Personal Experiences with the Combined Action Program in Vietnam - US Marine Corps Center for Emerging Threats and Opportunities
The Combined Action Platoon in Iraq: An Old Technique for a New War - First Lieutenants Jason Goodale and Jon Webre
Revive Combined Action Platoons For Iraq - Marcus Corbin
Introduction to 2/7 Combined Action Program (CAP) Platoon Actions in Iraq - Lieutenant Colonel P.C. Skuta
US Marines Combined Action Platoons - CAC/CAP Web Page
The Village - Bing West's classic at Amazon.com
Comments
A new Thesis on CAP units in Viet Nam by Jeannie Johnson
https://www.dropbox.com/s/huskhpipmmjs1t3/Jeanies%20thesies.pdf
A couple of other useful references that discuss CAPs in Vietnam include:
Andrew Krepinevich Jnr, The Army and Vietnam, John Hopkins University Press, Baltimore, 1986, pp. 172-175.
Robert D. Ramsey III, 'Advising indigenous forces: American advisors in Korea, Vietnam and El Salvador, Global War on Terrorism Occasional Paper 18, Combat Studies Institute Press, Kansas, 2006, pp. 30-48
Great list of references but you left off at least one. Read about the CIDG program in COL Kelly's book US Army Special Forces in Vietnam 1961-1971: http://www.history.army.mil/BOOKS/Vietnam/90-23/90-23C.htm