EGYPT, by sending its own troops to the defense of Saudi Arabia, has sharply changed the politics of the resistance to Iraq.Other Arab countries, perhaps Morocco and Syria, are reportedly preparing to send similar forces. One danger in the rapid American airlift into the Saudi desert was the opportunity that it offered Iraq's President Saddam Hussein -- an opportunity that he has been vigorously exploiting in his calls for holy war -- to portray it as a move by the West against an Arab army. With Egyptians in the line against him, that claim becomes less plausible.

The Iraqi invasion of Kuwait constitutes aggression by one Arab country against another, and when the Arab League met last week there was much talk about the need for an Arab solution. But Iraq is unlikely to respond to exhortations and denunciations. President Hosni Mubarak of Egypt, a realist, said yesterday that he sees no hope for a peaceful resolution of the invasion. That's a pessimistic view, but it is widely held and it suggests that, if the Arab governments are to have an active and influential part in settling this affair, they are going to have to have troops at the places where it is to be settled. Egypt now has men there.

That not only undercuts President Hussein's charges that the issue lies between the United States and the Arabs. It equally undercuts his cry that he is waging war on behalf of the many poor Arabs against the few very rich ones of the Persian Gulf. There is more than the usual amount of hypocrisy in that one, for Iraq's enormous oil reserves would have made it one of the richest countries in the world if its present leadership had not squandered its wealth, as well as hundreds of thousands of lives, in eight years of war with Iran. Egypt has three times Iraq's population and a fraction of its oil production, but it is on the other side of the skirmish line now forming in the desert.

It is heartening to see Egypt exercising leadership in the strategy to force Iraq out of Kuwait. For the United States and Europe, the primary interest in political stability there is the flow of oil. Iraq's neighbors have much more at stake. Iraq has made it clear that its intentions go beyond this month's conquest. It proposes to make itself dominant among the Arabs. Saddam Hussein has been claiming, in recent days, to speak for all the Arab world in a great test of will and of strength with the Americans. But most of the Arab world denounced him Friday in the Arab League's meeting, and now Egyptian forces as well as Americans face him at the Saudi border.