sentences:  The area was surrounded by security forces; two helicopters were brought in to monitor happenings and ensure a tight link with Bucharest, although the official reason for their presence was to fly mining accident victims to the hospital.The number of Securitate and Militia forces at Petroșani was doubled and military units were placed near all mines in the Jiu Valley.Securitate agents were hired as miners, not only to inform on other workers, but also to exert psychological pressures on them and even beat them before witnesses so as to create a climate of intimidation.