Strategic Systems Programs (SSP) intends to issue a request for proposal on a sole-source basis in accordance with Federal Acquisition Regulation (FAR) Parts 6 and 15 to The Charles Stark Draper Laboratory, Inc. (CSDL), 555 Technology Square, Cambridge, MA 02139-3539, the design agent and incumbent sole-source prime contractor for the TRIDENT II D5 Strategic Weapon System Guidance Subsystem. This effort will seek cost-plus-incentive fee (CPIF), cost-plus-fixed fee (CPFF) and fixed-price-incentive-fee (FPIF) type line items for Trident II (D5) Guidance and Reentry Systems including: Tactical Engineering Support; Fleet Support Services; Test Equipment Support; Common Missile Compartment (CMC) Support; Research into Guidance, Navigation and Control (GN&C) technologies; Design and Development of future TRIDENT II (D5) GN&C technologies; and Repair of MK6 MOD1 Guidance Systems and associated parts. Major subcontractor support is anticipated to be provided by Honeywell International, located in Clearwater, FL, General Dynamics Mission Systems, located in Pittsfield, MA, Raytheon, located in El Segundo CA, and Moog, Inc., located in East Aurora, NY. This effort is inextricably linked to work already being performed by CSDL under SSP Contract N00030-22-C-6002, which was awarded using other than full and open competition. Interested vendors for lower tier subcontracting opportunities should contact these entities directly. A solicitation is not intended to be posted on the Government Point of Entry and instead directly with the subject contractor in accordance with the sole-source procedures under FAR Part 15.