how did the u-2 incident contribute to the cold war?

Answer 1

click here:http://en.wikipedia.org/wiki/U-2_Crisis_of_1960

Answer 2

Bottom line is that it derailed the Vienna Conference that was supposed to take place between Kruschev and Eisenhower in May of 1960.
If that summit had taken place, many of the issues that drove the Cold War in the 1960s might have been settled.

For a good essay on the topic of the U-2 flight and the Cold War, see What If? 2: Eminent Historians Imagine What Might Have Been by Robert Cowley