We don't have synonyms for milstar yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are militar.
(N) :
(Military Strategic and Tactical Relay) a constellation of military communications satellites in geosynchronous orbit, which are operated by the United States Space Force, and provide secure and jam-resistant worldwide communications to meet the requirements of the Armed Forces of the United States.
(N) :
(Military Strategic and Tactical Relay) a constellation of military communications satellites in geosynchronous orbit, which are operated by the United States Space Force, and provide secure and jam-resistant worldwide communications to meet the requirements of the Armed Forces of the United States.