An individual who has served honorably in a branch of the United States military might be eligible to become a citizen based on that service. The U.S. Army, Coast Guard, Air Force, and Marine Corps are among the branches considered. Additionally, some who have served in the National Guard or in the Ready Reserve may be eligible for naturalization.
In order to be eligible for citizenship during peacetime, a current or former member of the military must be at least 18 years old. A minimum of one year of service must have been rendered honorably. A candidate for citizenship who is no longer in the military must have been honorably separated from service. Those seeking citizenship on this basis must have permanent residency at the time of taking a naturalization exam and must demonstrate the ability to communicate in English through reading, writing, and speech. Additionally, knowledge of U.S. civics and history is required. A residency requirement of five continuous years in the country is applicable unless a candidate is still in the service or is withing six months of their separation.
Those who serve honorably during times of hostility may be able to obtain citizenship after serving any period of time. As in peacetime, a candidate must be able to communicate in English and must have basic knowledge of the history and government of the United States. In both peacetime and during hostilities, an applicant for citizenship must demonstrate a pattern of good moral character and an attachment to the country's principles. Family members may also file for posthumous citizenship for an individual who has died in service of the country.
An individual who is unsure of the process for seeking U.S. citizenship in connection with military service may want to work with an immigration attorney to ensure that all qualifications have been met. Additionally, the attorney may help in coordinating the completion of applications and submitting them.
Source: US CIS, "Citizenship for Military Members", December 09, 2014