About 14 years ago, before the Israeli Disengagement from the Gaza Strip, which was achieved by my government expelling all of the Jews who had lived there and who had turned sand into an agricultural powerhouse, there was a widespread campaign in Israel that I was party to, with the goal of trying to explain why the disengagement wasn't a good idea. We actually tried to explain that it was a bad idea, very bad. The campaign was a door-to-door effort to enter the homes of Israelis and engage them in a serious conversation. This is much more difficult than it may sound. Think of it: knocking on the door of someone you've never seen and trying to discuss a serious issue with them. Think of it from the residents' point of view: here's this total stranger knocking on you door and who wants you to let him or her in so as to try to convince you that the planned disengagement is a bad idea. Why would you let some stranger into your house?Of course many doors didn't open: some people were out and some just didn't open. However – perhaps surprisingly, although in Israel it's less surprising than you think – many did open their doors. Having passes the first hurdle of getting the door open, the next hurdle was to convince the residents to let you in, because otherwise the conversation at the door may be a very short one.At one penthouse a man opened the door and held it with his hand, as if the door was still partially closed with the chain. In a very friendly manner he said: "Sorry, I'm basically against your viewpoint; I'm for withdrawal from all the territories". He meant he was for Israel contracting into its tiny, indefensible 1949 Armistice lines.I countered: "I'm with you, ok? Let's assume you withdraw every soldier and you have expelled every Jew and built a big fence: Jews on this side and Arabs the other side (of course Arabs would be on both sides, but that wasn't part of my point). Now my question is simple: if 10,000 Arabs, say women and children, come to the fence with cutters in their hands and start cutting the fence – what are you going to do?" I didn't bother with asking what happens if rockets come over the fence or fighters tunnel under it, just the simple question. With that question – the man let me into his house for further discussion.And that's the question: when civilians, say tens of thousands of civilians, are encouraged by an entity ruling over them and the land where they reside, an entity that loudly proclaims its intention to wipe your state off the map and kill your people wherever they are found in the world – that entity is Hamas in Gaza – so when civilians are encouraged by Hamas to break down the Israeli border fence, what is Israel to do?What would you do if I came through your door, or window, and sat down in your living room, with all my large family, and claimed that your house is really mine and demanded that you pack up and leave – what would you do?Well, it's a peaceful march, you say, and you can't shoot at peaceful people. (It's not a peaceful march, and the goal is to destroy Israel – but I'll let that go for now.) A peaceful march, and you can't stop it?That's wonderful! Only I don't understand something: why would any country waste money on building an army when all you had to do – if you wished to conquer your neighbor – was to just have your people march into the neighboring country? I mean: have 100,000 people march, or one million, and that's it! You've conquered your neighbor! Without firing a shot! Without even having a single gun!Sounds crazy, right? It is! Because if Hamas has people march on Israel – it's a march or war by definition, even if they fire no shots… for now.That's why Israel has every right and a sacred duty to defend its border, and to use lethal force to secure its border, if necessary. It's so simple!