From the Military Archdiocese website:
"The Diaconate and the Military Archdiocese"
This statement is intended to reply in a general and informal way to those who have requested information about the status of Catholic deacons wishing to be of service to the Archdiocese for the Military Services.
The present situation
The Archdiocese for the Military Services (AMS) does not provide a training and education program for deacons nor does it fund such a program. With few exceptions, all training and education is carried out under the auspices of a civilian (arch)diocese in the United States. It should be noted, however, that not all (arch)dioceses conduct such programs. Military members wishing to learn more about the diaconate should contact the nearest (arch)diocese in the U.S. to inquire about its diaconate formation program.
There are two ways in which deacons presently serve the AMS: (1) on active duty in uniform or (2) in a civilian capacity. Deacons on active duty function on a full-time basis in their primary military occupational specialty while providing support to a local military Catholic priest-chaplain as deacon on a part-time basis.
No deacons are ordained for service to the Archdiocese for the Military Services. A man is ordained a deacon for service to a specific (arch)diocese, even though he may be on active duty in the military or supporting the military in a civilian capacity. The presumption is, in each case, that a deacon on active duty in the military will report to the (arch)diocese for which he is ordained upon completion of his military duty unless the local Ordinary determines or permits otherwise.
Every deacon who wishes to minister within the Military Archdiocese— whether on a U.S. military installation or at a Veterans Affairs Medical Center, must first receive written permission from his Ordinary before applying to the Military Archbishop for faculties. Additionally, his ministry must be specifically requested by the senior priest-chaplain of that installation who, in turn, will act as the deacon's supervisor.
The duties carried out by deacons in the Military Archdiocese are essentially the same as those performed in civilian parishes. The deacon may be authorized to preach, carry the Blessed Sacrament to the sick at home or in hospitals, distribute Holy Communion during Mass or at other times; baptize, witness marriages, provide religious instructions, prepare individuals and couples for marriage, coordinate or direct programs for religious education and engage in various other activities under the supervision of the senior Catholic priest-chaplain.
Some of his ecclesiastical responsibilities may parallel, complement or be complemented by the work of Extraordinary Ministers of Holy Communion (EMHCs), lay leaders, lectors, Directors of Religious Education and others.
The deacon in military uniform ordinarily will not be financially remunerated for his work. A deacon serving the military community as a civilian may receive financial remuneration, but this would be an arrangement made by him through military or VA channels.
Finally, in answer to questions concerning deacons serving as "chaplains" in the AMS, only ordained Catholic priests may minister with the title "chaplain" since they enjoy the faculties proper to the priesthood and, therefore, can celebrate Mass and provide the faithful with all the sacraments.
Who am I to argue with the policy of the Military Archdiocese? I also took the time to look at Canon Law with regard to "Chaplains". In reading Canons 564-571, it is clear, and I stand corrected, that from a Roman Catholic Church perspective, Chaplains must be Priests.
Can. 564 A Chaplain is a priest to whom is entrusted in a stable manner the pastoral care, at least in part, of some community or particular group of Christian faithful, which is to be excercised according to the norm of universal and particular law.
Can. 566 - 1. A chaplain must be provided with all the faculties which proper pastoral care requires. In addition to those which are granted by particular law or special delegation, a chaplain possesses by virtue of office the faculty of hearing the confessions of the faithful entrusted to his care, of preaching the word of God to them, of administering Viaticum and the annointing of the sick, and of conferring the sacrament of confirmation on those who are in danger of death.
The two canons above pretty much eliminate the possibility of Permanent Deacon "Chaplains" at least from a Catholic standpoint. However, it is still hard to believe that a Permanent Deacon, particularly one who may have spent a number of years, if not his entire career, in the military could not serve in some full time capacity to help eliviate the severe shortage of Catholic "Chaplains" in our armed forces. These men would have a unique ability to relate to the men they were serving. And would it not be in the tradition of the diaconate for these men to serve those who are not currently being served? I have heard countless stories of military men and women months without seeing a Priest. Inevitably many of them end up going to protestant church services. Imagine the nominal Catholic that decides he really needs God in his life. Looking for someone to talk to he goes to the protestant chaplain, because there is no Catholic chaplain. I'm sure you can play out the rest of the scenario.
I am certainly not suggesting that Permanent Deacons replace Priests as chaplains. I am suggesting that Deacons might be able to handle many elements of ministry that they can do in order to free up our priest chaplains to do what only they can do - hear confession, celebrate Mass, annoint the sick and confirm.