***ONLY SEAPORT MAC HOLDERS are eligible for award under this solicitation.*** Request for Proposal (RFP) under the Seaport NxG Multiple Award Contract (MAC), number N6133126R3105 for Modeling, Simulation, Engineering, Analysis, and Tactics (MSEAT). This RFP will also be posted within the Seaport NxG Opportunities Page. This effort has been previously been posted within the Seaport NxG portal under the Opportunities page as the following: Source Sought Notice N61331-25-SN-Q38, dated 7/11/2025 and the follow-up Advance Planning Notice/Pre-Solicitation Notice dated 11/7/2025. Previous references this potential solicitation as number N6133126R3006. *** RESPONSES MUST BE SUBMITTED VIA THE PIEE SOLICITATION MODULE.*** PLEASE UTILIZE THE DOCUMENTS FOUND WITHIN THE SEAPORT NxG ANNOUCEMENT, Opportunity - Modeling, Simulation, Engineering, Analysis, and Tactics (MSEAT) RFP N6133126R3105. Opportunity Type: Other. *** Please refer to the Amendment Log found within the Seaport announcement for updates to the RFP.