This is a Sources Sought notice to identify qualified small businesses capable of supporting the development of radiation and nuclear medical countermeasures, not an active solicitation. The anticipated contract is a single-award IDIQ with a 7-year period of performance from on or about July 1, 2027, through June 30, 2034. The scope includes five task areas: administrative support, animal model development, non-clinical studies, chemistry/manufacturing, and Phase I clinical studies. The work will support the progression of candidate products toward FDA approval, primarily following the FDA Animal Rule. Interested small businesses must submit capability statements by 3:00 PM EST on February 17, 2026.