Complex sentence: Tensions increased when the US announced they would deploy Pershing II missiles in West Germany, followed by Reagan's announcement of the US Strategic Defense Initiative, and were further exacerbated in 1983 when Reagan branded the Soviet Union an "evil empire".
Split into simpler sentences: Tensions increased when the US announced they would deploy Pershing II missiles in West Germany, followed by Reagan's announcement of the US Strategic Defense Initiative. East and West tensions were further exacerbated in 1983 when Reagan branded the Soviet Union an "Evil empire".