As this is a role that fill a government PSC (Personal Services Contractor) role, "interview" is to determine if you will accept salary, have a security clearance, and if they can use your resume for their bid.

they send you to the govt for interview lots of paperwork and interviews....before you can get overseas...Its the various permits and approvals that take time. However you need to be prepared for both technical and managerial questions. The government just want to make sure you are competent enough suppose you are left there alone