Service in the US armed forces ought to grant US citizenship. Anyone who serves a hitch, especially in wartime, and especially a hitch in a combat zone, is a plenty good enough citizen for me. An honorable discharge ought to be good for the soldier, and his wife and kids to become citizens.
Why? The armed services attract the very best people. And they are loyal to the country. The men I served with in the US Air Force were all the best people you could ever want to see. Far as this veteran can tell, the current crop of service men is every bit as good. We strengthen the United States by admitting people like that to citizenship.