Under Public Law 101-249, relatives of someone who died as result of being an active member of the US military during a period of war or military action may file immigration Form N-644 (Application for Posthumous Citizenship) on behalf of the deceased. Form N644 grants posthumous citizenship to the deceased as a commemoration of the sacrifices (and the ultimate sacrifice) that person made for the United States. Since many non-US persons who serve with the United States Armed Forced are very loyal to American values and are willing to risk their lives for the United States, the US government allows Form N644 to be used to commemorate and honor this bravery.
It is important to note, however, that filing Form N 644 and being approved for posthumous citizenship only serves to say that the deceased was a United States citizen at the time of death. It is purely a honorary status and not a traditional form of citizenship. This means that citizens of someone who receives posthumous citizenship through USCIS Form N-644 are not eligible for any privileges or benefits of citizenship. Someone who is a relative of a person who has received posthumous citizenship through Form N-644 may not apply for a green card based on the fact that they are related to a US citizen, for example.
If you file Form N644 on behalf of a relative and your application is approved, you will receive a Certificate of Citizenship (N-645) in the name of your relative. This is similar to receiving posthumous military honors or awards. Again, having a relative approved for citizenship through N 644 will not assist you with immigration to the United States. If you wish to immigrate to the United States, speak with a qualified US immigration attorney or refer to the USCIS website to find out how you might qualify to immigrate to the US.
Currently, USCIS Form N-644 is four pages long and is free to file. Anyone who has died as a result of being in active duty with the Armed Forces of the US after 11 September 2001 is generally eligible for the Application for Posthumous Citizenship. There is no cap or limit on the number of citizenships which can be granted per year with immigration Form N-644. However, the number of posthumous naturalizations granted tends to be quite small, simply because the majority of US military members are US citizens. As well, of those non-US active service members who pass away in active duty, not all have relatives who wish to seek posthumous citizenship on their behalf.