This problem is unique and characterises the fast-shifting situation in the Middle East.
The unstable situation in Egypt is a cause of great concern to Israel. Since the peace treaty between the two countries was signed in 1979, the Israeli defence forces (IDF) have considered Egypt not as a friendly country, but rather as a "cold friend" that poses no threat.
This situation ended when President Hosni Mubarak was ousted. If there was hope that some sort of steady regime will replace the one that ended its historic role, it has faded. Even the elections that started yesterday in Egypt are not relaxing the tension.
Egypt has a huge army, including a modern air force. The problem Israel faces is how to monitor and detect any signs of hostility without breaching the sovereignty of Egypt.
The situation is even more complicated because the Sinai Desert has become a haven for extreme Islamic organisations.
So Israel is using all its standoff intelligence-gathering resources to monitor the situation. Spy satellites, oblique photography and optical payloads on tethered balloons are doing the monitoring job.
The fact that the Sinai Desert became the "wild south", with no real control by the Egyptian armed forces, causes some other concerns that require the attention of Israel.
One result - the C-Music system developed by Elbit Systems to protect Israeli airliners from shoulder-launched missiles - will also be installed on aircraft that fly from central Israel to Eilat, the Israeli resort on the Red Sea.
The route is in close proximity to the border and the Sinai is full of well-armed terrorists.
Updated intelligence points to the fact that a great number of shoulder-launched missiles, most of them from Libyan army depots that were looted during the upheaval, found their way to the Sinai.
So Israel, actually its airforce, now has a new task - how to see what is happening across the border, using only the keyhole without opening the door.