This definition appears very rarely
Samples in periodicals archive:
PAMUSA [AR 310-50] post attack mobilization of the United States Army; 3 provisioning relational integrated and distributed electronics...
PAM USA - Post-Attack Mobilization of the United States Army PANAGRA - Pan American Grace Airways, Incorporated P ANAR - Panoramic Radar PANB - Panic Bolt
PAMUSA: Meaning of Acronym Language Category; Post Attack Mobilization of the United States Army : Acronym in English: Military, Acronym