Sinai is Israel's last open border: 230 kilometers (about 143 miles) of breathtaking views, virgin terrain virtually untouched by bulldozers. In the next two weeks, Chief of Staff Dan Halutz is expected to present the prime minister and finance minister (if, indeed, there is one) with a plan to seal off the border: 80 kilometers (about 50 miles) of security fence, similar to the one that currently separates Israel from Gaza and from large parts of the West Bank. Along the rest of the border, the plan calls for electronic fencing. The estimated cost for the project is NIS 1.5 billion (USD 320 million), and IDF sources say Sharon is leaning towards approving the plan. Building the fence will show Israelis the extent of the revolution that has happened in recent years on the southern border. The fantastic views are still there, as are the scuba diving sites and the biblical wilderness, but inside it all there have been developments of a very different nature. Terror base For years Sinai has served as a base for drugs, weapons, and people smuggling into Israel. This criminal activity planted the seeds for terrorism. The Gaza disengagement worsened the situation. What was previously difficult to smuggle through tunnels now moves openly, with no danger. Large amounts of weapons and ammunition have entered the Gaza Strip. Terror activists have left Gaza for Sinai and tied to move from there, through Israel and into the West Bank. The IDF is convinced we are approaching the day when suicide bombers from Gaza will be sent from Gaza to Sinai to population centers inside the Green Line. Target: Ben-Gurion Airport? Previously, Gaza's contribution to the suicide bombing market was small they were simply stopped by the fence surrounding Gaza. Now, they can get around that and reach Israel via Sinai. Pessimists say there is a real danger that Sinai could become a base for Hizbullah and al-Qaeda. One, a senior politician, believes terror cells armed with shoulder-launched anti-aircraft missiles will infiltrate and will try to shoot down a plane over Ben-Gurion Airport. Such an event would be an economic and human tragedy on a scale Israel has never known, said the source. Was Gaza move a mistake? So leaving the Philadelphi Route was a mistake? Depends on who you ask. Chief of Staff Halutz believes Israel is far better off today than before we left Gaza. There were worrying signs from Sinai a long time before the IDF left Gaza, and if someone wanted to smuggle weapons from Sinai, he wouldn’t need to come through Rafah. He could just as easily do it from Egypt or Jordan. For most Israelis, it is easy to think of Gaza as enemy territory, as they do about Syria and Lebanon, perhaps even about Egypt and Jordan. But Sinai? That peaceful peninsula, a land of cheap shopping and no worries, has all of a sudden become such a matter for concern? If I was advising terror organizations, I would tell them, "let them have Gaza, don't worry about Nablus or Hebron. They can even have al-Aqsa. Just don't let them touch Sinai." Nahum Barnea is a columnist for Israel's leading newspaper Yedioth Ahronoth