Justification for Other than Full and Open Competition. The Defense Threat Reduction Agency (DTRA) contracting activity proposes to procure, without using full and open competition, a continuing effor... Justification for Other than Full and Open Competition. The Defense Threat Reduction Agency (DTRA) contracting activity proposes to procure, without using full and open competition, a continuing effort entitled “Research & Development Directorate Advisory and Assistance Service Support” via a contract modification to the current Research & Development Advisory and Assistance Services contract with ARServices, Limited (ARServices).