Actually, both sides of the fence are built on Palestinian land in many places. And then Israel imposes a no-go zone for the Palestinians on their side. Yet, Israel crosses into Palestine whenever they feel like it. In fact, those brave soldiers defending Israel hide in trenches and behind bushes to ambush the young Palestinians.
Law expanding definition of terrorist activity passes first Knesset reading (Haaretz)
from the article: Report: Four Palestinians wounded by IDF fire in northern Gaza Strip