CAIRO -- With full-scale war now started, Egyptian President Hosni Mubarak, the gung-ho former Air Force pilot, confides to aides that he wants his own troops "in the front edge of attack" on Kuwait.

When Mubarak says privately that "I sent them there to fight," he means it. But around him, and throughout this densely populated land of soft-spoken, peace-loving Nile River fellahin, the mood was somber as the violent storm breaks.

The conflict between Mubarak's confidence and his people's sobriety frames the highly uncertain future facing the most populous Arab state. Mubarak and Egypt will be the Middle East's big winners if the war against Saddam Hussein goes as predicted by specialists who are certain of the alleged technological wonders of American arms. But if it turns sour, Mubarak and Egypt could pay dearly.

"The president is too militant for me," an Egyptian opinion leader who knows Mubarak well told us. Many here agree with that mild rebuke, which explains why Mubarak is extremely cautious in his public pronouncements. His bellicosity is concealed from TV, radio and press.

He has sent more troops to the Saudi desert than publicly acknowledged. In addition to his two classiest divisions, the 3rd Mechanized and 4th Armored, he has made Saudi Arabia's King Fahd a gift of specialized military police units to help with expected law-and-order problems in the holy places of Mecca and Medina.

Foreign Minister Abdel Meguid told us that it is "already a catastrophe that the Arab world is going to war." Nevertheless, he agrees with his president that violent reaction from Arab masses is unlikely no matter how skillfully Saddam appeals for support as a modern-day Saladin battling the infidel.

That cheerful opinion is far from universal. Mohamed Hassanein Heikel, a prominent voice on the Egyptian left, told a huge audience at the Cairo Book Fair Sunday that Saddam is already a hero in the street in some Arab countries, but not Egypt. From the audience came shouts: "No, no" -- meaning he is a hero here, too.

A U.S. source closely tied to Cairo's political and social elite told us that anti-American feeling is on the rise here and could become "bad." But if such sentiment exists, so far it is hidden. Ambassador Frank Wisner has not authorized the departure of any dependents of U.S. Embassy officials, and Washington has not yet recommended it. That makes Cairo unlike Amman and Damascus.

Whether this political passivity survives the fighting depends on what kind of war envelopes the region and how much anti-American terrorism it spawns. The official line is that Saddam's Iraqi forces will collapse quickly before U.S. air power.

In this scenario, a presidential adviser told us -- clearly reflecting Mubarak -- the United States "will finish the unfinished business of Vietnam, Iran and Lebanon." Saddam's troops, he said, "have no motivation." He based that speculation on Egyptian army officers who have "advised" Saddam's army in the past.

But many skeptics here ask: How can we be sure? And top Western diplomats say privately that if this prediction of a quick, decisive victory proves to be wrong, the United States and Egypt could pay a heavy price -- savage in the case of Egypt. The stakes are high here. As President Bush's most important Arab ally, Mubarak will cash in on that new intimacy if the war is won speedily. No other Arab state, including Saudi Arabia, could gain as much.

But if the easy forecasts of a six-day (or shorter) war are wrong and thousands of Arabs die in the fighting, a nationalist firestorm against Egypt's leaders could transform the political scene and destabilize the country. Mubarak rules that out, saying in private that it just cannot happen. Many others, both Egyptian and Western, are not nearly so sure.