Mubarak was on the US/Israeli payroll. Now that it appears like the Egyptian people are finally going to control their own country, I expect they will raise the issue of Israel executing Egyptian POWs at some point in the future.
In 1956, Egypt nationalized the Suez Canal on the western side of the Sinai Peninsula, and thereafter prohibited Israeli ships from using the Canal, owing to the continuing state of war between the two states. Egypt also prohibited ships traveling to and from Israel from using Egyptian territorial waters on the eastern side of the Peninsula, effectively imposing a blockade on the Israeli port of Eilat. Subsequently, Israeli forces, aided by Britain, and France (which sought to reverse the nationalization and regain control over the Suez Canal), invaded Sinai and occupied much of the Peninsula within a few days (see Suez Crisis). Several months later, following strong pressure from the United States and the Soviet Union, Israel withdrew its forces from Sinai. Thereafter, the United Nations Emergency Force (UNEF) was stationed in Sinai to prevent renewed conflict between the two states in Sinai.
In 1967, Egypt reinforced its military presence in Sinai and renewed the blockade of Eilat. The purpose of that deployment was most likely about taking back control of the Sinai, not invading Israel since on May 16 Egypt ordered the UNEF out of Sinai and Secretary-General U Thant eventually complied and ordered the withdrawal.
I'm sure that many Egyptians soldiers near the Israeli border made Israel nervous, especially given the Nasser's rhetoric and posturing. But the Israelis knew Egypt wasn't ready for a war with them in 1967. Most of Egypt's military was bogged down in the Yemen civil war at the time. If Egypt was really preparing to invade Israel rather than just taking back control of the Sinai, likely they would have pulled out of Yemen first.
BTW, I'm not condemning Israel for their "preemptive" attack against Egypt. War with Egypt was inevitable. Egypt occupied the Sinai in an awkward uncoordinated manner. Israel saw an opportunity to kick Egypt in the nuts, and didn't hesitate. All is fair in love and war, so they say. My point was that Israel initiated the 1967 war, not their Arab neighbors.
I'm also not condemning Japan for their "preemptive" attack against in the US. I will condemn Imperial Japan for their brutal occupation of China, Vietnam, the Philippines, the rape of Nanjing and other cities... and all the other atrocities they committed. But the Pearl Harbour attack was limited to strictly military targets. The US was threatening Japan's domination of the far east. Japan's economy was and still is completely dependent on import oil and most other raw materials. The American economic embargo seriously disrupted the Japanese economy and was an act war. The US arrogantly thought the Japanese would never dare to initiate a war with them and left themselves vulnerable to attack, just like the Egyptians did in 1967. Just like Israel, Japan's leaders saw an opportunity to kick the US in the nuts and they didn't hesitate.
All's fair in Love and War. Japan, like Israel has the right to initiate war. Japan was eventually crushed. Meanwhile Israel continues to commit atrocities.