Unauthorised Access: Physical Penetration Testing For IT Security Teams

D.1.3. Levels of Clearance in the United States

Security clearances in the United States are issued along broadly similar lines to clearances in the United Kingdom and the terms used (SECRET, CONFIDENTIAL, etc.) are completely compatible between the two systems. This is largely due to the fact that the United Kingdom has been consciously copying the United States in security-related matters since World War II.

There are, however, some important differences. Put simply, a security clearance in the United States is granted according to the level of access it provides, for example a 'Secret clearance' grants access to SECRET documents (though naming conventions vary). The exception to this is levels above 'compartmentalized access', when an individual is given access to a particular type of data. Another important difference is that for certain types of clearance you may be required to take a polygraph (lie detector) test.

Security clearances are arguably taken a lot more seriously in the United States and consequently take a lot longer to approve. For example, in the United Kingdom, an SC clearance takes about three months depending on the backlog whereas a US Secret clearance can take as long as a year.

D.1.3.1. Confidential or Level 1 Clearance

This is broadly similar to the UK BC level of clearance and typically requires a few weeks to a few months of investigation. A confidential clearance requires a National Agency Check with Local Agency and Credit Check (NACLC) investigation ...