Captain Yotam, a reservist officer sitting in front of the control console at Mount Meron, is communicating with a pair of F-16I fighters, somewhere over the Mediterranean. The pilots set off to check into a warning about a suspicious civilian aircraft moving dangerously close to an area that Israel considers sensitive - the Tethys Sea offshore platform west of Ashkelon, drilling for natural gas.

The lead pilot reports that he has identified a foreign warplane moving near the civilian aircraft, and is hiding behind it. The dilemma facing both the pilots and the captain at the controls is complex: How can they shoot down the fighter plane if it attempts to enter the no-fly zone without hitting the civilian airliner?

"Authorized to shoot down the fighter, only, without harming the civilian," the controller says. "In the final decision, you are allowed to target the fast mover [fighter], and at the same time try to divert the civilian to the west using accepted signals. Try moving him west to avoid entering the sensitive area."

At the same time, the control center is also handling several other troubling incidents. A fighter training near the border has crossed into Israeli territory. Another aircraft was located flying slowly in the south, too close for comfort to the Dimona reactor. Communicating, collecting information and making decisions all happen simultaneously, within just a few minutes.

Everything, of course, is part of a workshop on "air terrorism," organized by the Israel Air Force earlier this month. Many air force squadrons and several command and control centers took part. The scenarios were based on reasonable possibilities for Israel or on cases that have already happened elsewhere.

Much of the exercise was carried out at the control center on Mount Meron. At 1,200 meters, it is one of the highest peaks in Israel, but the controllers work deep underground, in a facility capable of withstanding air attacks.

In May 2006, not long before the Second Lebanon War, Hezbollah fired a rocket at the base. In the event of a full-blown war, the base would be hit with much more.

According to Lt. Col. Gil, who runs the northern command center and says Israel's readiness for stopping air attacks, and primarily suicide attacks with the use of an aircraft, has undergone massive restructuring since 9/11.

Several months prior to the attack on the Twin Towers, a civilian pilot from Lebanon flying a Cessna crossed into Israeli airspace and was brought down over Michmoret, north of Netanya. The pilot was suspected to be a Hezbollah supporter.

"Today he would not have gotten further south than Nahariya," Gil says.

A fighter jet moves at a speed of 14 kilometers per minute. Which means in three minutes it can cover the distance from Rosh Hanikra to the refineries in Haifa, or from the Dead Sea to Jerusalem. This means endless surveillance of the air traffic in neighboring countries is required, using a quick warning system and permanent readiness of interceptors.

On alert 24-7

"Thousands of aircraft, most of them civilian, fly around us all the time," says Col. Ran, who heads command and control of the air force. "This requires us to be alert and follow any unusual flights. If there is a terrorist incident in Greece, we raise alert readiness and follow the situation in case the problem slides over to us. And when there is a suspicious incident in the Tel Aviv skies, we also go on alert in Eilat. Our assumption is that this may be a combined attack, which may include a diversionary attack."

Under certain circumstances, the decision to shoot down an aircraft may be up to the colonel who happens to be commanding the control center. More complex situations would involve more senior officer, the command center at Air Force headquarters, and maybe even the political-military leadership: the prime minister, defense minister and chief of staff.

Every week urgent calls are made to track down a senior political figure, or his military secretary, as quickly as possible in order to make a decision. When politicians take office, they are also briefed on the relevant terminology and the decision-making timetable.

After September 11, "there is zero tolerance," says Lt. Col. Gilad, an F-15 squadron commander. "If I don't deal with a combat aircraft the minute it crosses the border, it will be too late. This is a routine task that is very tiring and requires readiness 24 hours a day, seven days a week, 365 days a year. It involves a lot of needless takeoffs, and significant expense."