In the light of "glasnost" and "perestroika", street demonstrations had been increasingly growing in popularity and support. On 23 August 1986, Black Ribbon Day demonstrations were held in 21 western cities including New York, Ottawa, London, Stockholm, Seattle, Los Angeles, Perth, and Washington, DC to bring worldwide attention to human rights violations by the Soviet Union. In 1987, Black Ribbon Day protests were held in 36 cities including Vilnius, Lithuania. Protests against the Molotov Ribbentrop Pact were also held in Tallinn and Riga in 1987. In 1988, for the first time, such protests were sanctioned by the Soviet authorities and did not end in arrests. The activists planned an especially large protest for the 50th anniversary of the Molotov–Ribbentrop Pact in 1989. It is unclear when and by whom the idea of a human chain was advanced. It appears that the idea was proposed during a trilateral meeting in Pärnu on 15 July. An official agreement between the Baltic activists was signed in Cēsis on 12 August. Local Communist Party authorities approved the protest. At the same time several different petitions, denouncing Soviet occupation, were gathering hundreds of thousands of signatures.