 There is speculation whether Jaruzelski instigated martial law to prevent bloodshed if the Soviets and other Warsaw Pact countries were to enter Poland under the mutual assistance treaty, like in the Hungarian Revolution of 1956 and the invasion of Czechoslovakia in 1968.On 13 December 1981, Jaruzelski announced the introduction of martial law in a televised speech addressed to the entire nation.The Polish People's Army, Citizens' Militia (MO), ZOMO special units and tanks rolled onto the streets to scare off demonstrators, begin regular patrols and maintain curfew.