Halfway through a 10-day tour in Israel, Risa Nagel had a decision to make.

Nagel, a 25-year-old grant writer from Seattle, had hiked the hills of Galilee and wandered the ancient market in Jerusalem. But then some of the friends she had just met told her they were planning to walk off the tour to visit a Palestinian family, an act of protest that was bound to cause pain and controversy.

"We will be able to see for ourselves what's going on," one of them told her. "Do you want to come?"

Nagel agonised. The next day, after the group