Despite the overall moderate tone and Marxist–Leninist orthodoxy, the "Two Thousand Words" called for action on the part of the public in case of military intervention and therefore denied the leading role of the party, as Vaculík's 1967 speech had. It was popular throughout Czechoslovakia with both intellectuals and workers, and its popularity only increased after the party officially condemned it. It also significantly increased the concerns of the Soviet Union. Following the "Two Thousand Words," Leonid Brezhnev's party leadership, seeing a situation similar to that in 1956 Hungary developing, used the term "counterrevolution" to describe the Prague Spring for the first time. If a counterrevolution was taking place (and the Soviet Union was increasingly disposed to categorising the events in Czechoslovakia as such, as other radicals continued to act and Dubček failed to gain their confidence), socialism as the Soviet Union saw it was threatened and invasion by Warsaw Treaty Organisation troops, as occurred 20–21 August 1968, was deemed justified. This policy of the acceptability of using force wherever socialism was thought to be threatened would become known as the Brezhnev Doctrine, and Vaculík's "Two Thousand Words" was an integral step toward this early application of it.