Reagan's rhetoric convinced the hardliners in the Kremlin that they faced a hostile enemy, delaying Gorbachev's much needed economic reforms after the long-suffering Soviet economy was finally broken by the Carter grain embargo (to which I give more credit than others do) and the invasion of Afghanistan.
From article on the subject:
Reagan's commitment to SDI made it more difficult for Gorbachev to persuade his officials that arms control was in the Soviet interest. Conservatives, some of the military leadership, and spokesmen for defense-related industries insisted that SDI was proof of America's hostile intentions. In a contentious politburo meeting called to discuss arms control, Soviet armed forces chief of staff Marshal Sergei Akhromeyev angrily warned that the Soviet people would not tolerate any weakening of Soviet defenses, according to Oleg Grinevsky, now Russia's ambassador to Sweden. Yakovlev insists that "Star Wars was exploited by hardliners to complicate Gorbachev's attempt to end the Cold War."http://www.theatlantic.com/politics/foreign/reagrus.htm