Q.  According to an acknowledgment email, the DOJ's National Security Division received our FOIA request on the 20th of July. Yet as of this time, there is no response. What are my options?

A.  The DOJ's response to your request was due within 20 business days, which by my calculation is August 17, 2018.  If "unusual circumstances" apply to your request, however, DOJ may notify you that it is taking an additional 10 business days to process your request.  Once the response deadline passes (whenever that may be), you are entitled to file a lawsuit in federal court.

Short of a lawsuit, you might consider asking NSD's FOIA public liaison for an estimated date of completion.  According to DOJ's most recent FOIA annual report, NSD takes an average of about 342 days to process "complex" requests and 31 days to process "simple" requests.  Thus, if the acknowledgment letter does not indicate which processing track your requests falls into, you should ask the NSD liaison.  

Other options include asking NARA's Office of Government Information Services for assistance.  Keep in mind, however, that OGIS cannot compel an agency to speed up a response.  Another means of prodding the agency would be to contact your Congressperson, who will then forward your concerns to the agency with a less-than-passionate request for assistance.