 Concern for U.S. citizens, and rules of engagement (ROE) that directed casualties be minimized, PSYOP loudspeaker teams, from the 1st Bn, 4th PSYOP Gp, became a key asset.When the PDF did not surrender after initial appeals, the message changed, with the tactical commander warning "that resistance was hopeless in the face of overwhelming firepower and a series of demonstrations took place, escalating from small arms to 105 mm howitzer rounds.Subsequent broadcasts convinced the PDF to give up.