In the Belarusian Soviet Socialist Republic, the publication of his works was banned: many Belarusian Soviet writers wrote open letters against him, calling him “an agent of the CIA,” “paid liberator of Belarus,” and “crazy anti-Soviet.” During the Expo 67 exhibition in Montreal, Kastus organized a protest against the USSR, starting to shout anti-Soviet slogans and scatter brochures. This was noted by Alexei Kosygin, and the police soon detained him. In 1992, he visited his historical homeland for the first time, but after 1995 his books again ceased to be published.