Borders that were established in 1948 by outside forces (including the USA) and expanded since with military aggression and the continued settlement of contested land. The insistence of the Israelis to build settlements (an indication that they plan to expand their borders) on land that historically belonged to someone else is a key point in the conflict.
If you want to talk about protecting land or protecting borders, you are backing the wrong side in this conflict. The land was taken from the Palestinians, who were too weak and disorganized at the time to resist. They are now fighting back to regain what was rightfully there's before it was taken following World War II.
Since you like to compare this situation with others. Here's a scenario for you. Someone takes your home and property by force. You are left homeless. Do you have the right to fight to regain possession of the home that at one time belonged to you? Based upon your previous logic, you are just out of luck. If you try to regain possession of your own home, you are a terrorist. You should just accept the fact that your home was taken by another. The Palestinians and, in particular, groups like Hamas would argue otherwise. They would argue that they have every right to do whatever is necessary to regain what they previously held as their historic homeland.
