North American leaders, particularly American leaders, spoke out against the Berlin Wall. President Kennedy visited the city in 1963 shouting "Ich bin ein Berliner". President Reagan visited Berlin in 1987. His speech, punctuated with the words "Mr. Gorbachev, tear down this wall!", left its mark. Only two and a half years later, the Berlin Wall came tumbling down (see http://alinefromlinda.blogspot.ca/2011/11/this-wall-will-fall.html).
Here is an excerpt from his speech:
"We welcome change and openness; for we believe that freedom and security go together, that the advance of human liberty can only strengthen the cause of world peace. There is one sign the Soviets can make that would be unmistakable, that would advance dramatically the cause of freedom and peace. General Secretary Gorbachev, if you seek peace, if you seek prosperity for the Soviet Union and eastern Europe, if you seek liberalization, come here to this gate. Mr. Gorbachev, open this gate. Mr. Gorbachev, tear down this wall!" (http://www.artofmanliness.com/2008/08/01/the-35-greatest-speeches-in-history/)