Administrative Processing/Security Advisory Opinion may be requested for a variety of reasons, below is some information to help inform an applicant of the process.
When is a Security Advisory Opinion (SAO) requested?
An SAO may be required of a visa applicant for a number of reasons: a “hit” during a name-check; being a “national” of certain countries; studying or researching an academic field on the Technology Alert List (TAL); or, based on the “intuition” of the interviewing officer.
NAME-CHECK… Every applicant for any visa must undergo a name-check through the Consolidated Consular Database (CCD). If the applicant’s name matches a name on the database as a ‘problem’, an SAO is required.
NATIONALITY… Being a “national” of certain countries is all that is needed in order to require an SAO. “National” may mean that the individual has dual citizenship, once was a citizen of one of those countries, OR was born in one of those countries. The only way to avoid this is if proof of renunciation of that citizenship is in writing (whether in fact the applicant was ever a citizen of the country).
TAL… Many of the fields of study listed on the TAL are very broadly stated which results in a number of SAOs. Detailed (but not lengthy!) explanations of the specific research that the applicant is engaged in may obviate the need for an SAO, if the research is clearly not of strategic importance, but this is not guaranteed.
INTUITION… Consular officers are asked to use their own impressions to request an SAO if they are at all unsure of whether it is necessary or not.
How long does an SAO take?
SAOs are a referral to “Washington agencies;” note the use of the plural form. Several agencies check the individual’s background through their own systems and pass the results back to a central point. It is never possible to find out exactly where the SAO is at any one point in time.
The U.S. Department of State claims that 80% of all SAOs are cleared within two weeks. There is no prediction ever made of the length of time it will take. Some posts may tell applicants the “average for an SAO is X weeks/months”, but this is anecdotal and only an AVERAGE for the recent experience of their post.
Anecdotally, many in the academic community have reported waits of two, four, six months and longer. If 80% are indeed cleared in two weeks, then 90% of the remainder are student and scholar SAOs. Reports of delays of eight months and more, while possible, are uncommon.
The above information was taken from here.