How many more Istanbulis are in Egypt's Army?

Lt. Khalid Istanbuli was a conscientious soldier, popular with his men, and religiously devout. Three security checks had cleared him to participate in Egypt's Oct. 6 military parade.

But he was harboring a plan that he and three other men -nonsoldiers but well trained in the use of automatic weapons -carried out during the parade: the assassination of Anwar Sadat.

Egyptian and American intelligence knew that Muslim militant groups were planning to attack key Egyptians, including President Sadat. Istanbuli was not known to be part of the plot. Sadat was confident of his safety.

That is the story of the assassination conspiracy as Egyptian and Western sources can piece it together. Because of it"

* Defense Minister Abdul Halim Abu Ghazzala has begun a purge of the Egyptan Army, so far firing 30 officers and 104 men believed to belong to either the Muslim Brotherhood, the Takfir Wal Hijra, the Jamat, or lesser groups. The head of the presidential guard, Gen. Bahmoud Masri, is reported to be under house arrest, and the guard itself is undergoing investigation for possible complicity in the Sadat assassination.

* Interior Minister Nabawi Ismail has announced the arrests of 230 Muslim militants believed involved in the assassination or the Oct. 8 mass murder of police in the southern city of Asyut. A further 2,000 fundamentalists and leftists have been detained.

In all, more than 3,500 Egyptians have been arrested since early September.

In society at large, militants have gone into hiding. But no one here is assuming that their threat has passed.

The big question today is how many other Istanbulis are there in the Army? It is difficult to tell, but Western analysts say they believe the Army is relatively more immune to penetration by militants than society at large.

The Army purge, however, does show there have been a number of coverts or infiltrators in the ranks. The investigation is continuing and Egyptian observers expect further arrests and firings of officers in the weeks ahead.

"We will have too show these people (Muslim militants throughout Egypt) that we will be very firm," a top Egyptian official told the Monitor. "Then we will have to argue with them intellectually to convince them that they are misguided."

A high-level Western diplomat says he is "convinced that fundamentalism is not growing in the Army" and that "the government can deal with these pockets of fundalmentalism."

The consensus among informed sources is that an Islamic revolution or coup is not in the offing. But Western and Egyptian analysts say authorities will have to keep up strict security, Muslim militancy will continue to attract followers, and attacks will recur.

"The regime has been dealing with the symptoms, not the phenomenon itself," an Islamic scholar points out.

In a recent study, Prof. Saad Eddin Ibrahim of the American University of Cairo observed that Muslim fundamentalism in Egypt is a reaction mainly to Western capitalism and peace with Israel. The movements themselves predate these policies but have gained followers as Westernization and the Camp David process have progressed.

Dr. Ibrahim's study shows that the movements attract mostly middleand lower-middle-class university students -usually young men from rural backgrounds who are idealistic and see little hope for their careers.

"The social profile of those who join radical leftist movements seems quite similar to that of Islamic militants," the study points out. But given Muslim hostility to Marxism, radical Islamic groups attract more followers.

The ultimate goal of each of these groups is takeover -by violent means if necessary -of Egypt and installation of an Islamic state. Most have training camps and caches of weapons -some of which have been seized in recent days -acquired on the Egyptian black market.