By 1987, the ethos of glasnost had spread through Soviet society: journalists were writing increasingly openly, many economic problems were being publicly revealed, and studies appeared that critically reassessed Soviet history. Gorbachev was broadly supportive, describing glasnost as "the crucial, irreplaceable weapon of perestroika". He nevertheless insisted that people should use the newfound freedom responsibly, stating that journalists and writers should avoid "sensationalism" and be "completely objective" in their reporting. Nearly two hundred previously restricted Soviet films were publicly released, and a range of Western films were also made available. In 1989, Soviet responsibility for the 1940 Katyn massacre was finally revealed.