They claimed Reagan's defense buildup would lead to war. They were wrong.
Perhaps Miller, in his old age, has forgotten that it was Reagan's material support for Saddam Hussein that led to both his power in the region, and his status as a potential threat to the United States. This, in turn, has led to two wars. If "they" claimed that Reagan's policies would lead to war, and those policies led to two wars, how might they have been wrong?