One hopes even Obama, inexperienced as he is, doesn't see all these "walls" as essentially the same in size and scope. But beyond the incoherence, there is a deeper problem, namely that "walls" exist not simply because of a lack of understanding about who is on the other side but because there are true differences in values and interests that lead to human conflict. The Berlin Wall itself was not built because of a failure of communication but because of the implacable hostility of communism toward freedom. The wall was a reflection of that reality, not an unfortunate mistake.
Tearing down the Berlin Wall was possible because one side -- our side -- defeated the other. Differences in levels of economic development, or the treatment of racial, immigration or religious questions, are not susceptible to the same analysis or solution. Even more basically, challenges to our very civilization, as the Cold War surely was, are not overcome by naively "tearing down walls" with our adversaries.
Heaven knows we all wish it were different. We all wish that we could end conflict in our world simply by a better "understanding" of our adversaries. But wishing doesn't make it so, and when America has enemies steeped in a murderous ideology, who fear and hate the very basis for its being -- freedom, and religious freedom in particular -- it doesn't matter how well we understand them, or how often we extend the hand of friendship. They will still want to kill us.