President Mobutu Sese Seko is credited with having salvaged from the rebel strike at Kolwezi at least a six-month respite thanks to Western military and financial help and the presence of a Morocan-led African security force.

But diplomats and other observers gauging the chances of proposed draconian reforms - which are generally thought the only way of avoiding Mobutu's fall and a subsequent chain of catastrophies throughout Africa - already note worrying signs of Euphoria overcoming the president.

In the wake of the past crises, that has been in the sign that Mobutu was preparing to squirm out of the seemingly foolproof constraints set by his foreign backers as the price for salvation.

This time he was saved by the fierce opposition to secessionist movements among other African leaders, the rebels' excesses, which outdid even those of Zaire's soldiery, and the feeling that Zaire was too important to be allowed to return to chaos.

"We don't want to give the impression just because Mobutu suffered a catastrophe in Kolwezi in losing mining revenue that the world is full of Santa Clauses," a Western diplomat remarked.

The core of the tough Western plan adopted last week in Brussels involves International Monetary Fund control of foreign exchange, customs and taxes in the national bank and finance ministries.

Mobutu lived with similar constraints in the late 1960s and until 1972 when copper prices zoomed and Zaire was considered out of its financial and economic difficulties.

Most of the recent Brussels decisions had been public knowledge for months. The rescue operation then was aimed at stopping a stagnant economy and inflation that has seen prices rise at least 70 percent while gross national product has declined between 5 and 7 percent in each of the past three years.

Thus, even before the Kolwezi fighting reduced foreign exchange earnings, Mobutu in theory had accepted the fact Zaire was facing its worst crisis since it became independent from Belgium in 1960.

In the "best case" scenario, Mobutu would reorganize his hated and ineffective army, reduce lavish personal spending, expand decentralization and the national assembly's powers, seek political reconciliation at home and abroad and achieve better management.

But few observers believe Mobutu capable of meaningful reform in light of past unkept promises, especially after the 1977 fighting in mineral-rich Shaba Province.

For example, government spending in 1978 was running twice as much as receipts despite promises to cut back.

Corruption has become so widespread that, in the words of one economist, "In Zaire it's a hurry to remain honest."

As was the case in the chaotic early 1960s, durables and American food aid routinely shipped across the Zaire River to the Congo in exchange for the hard, French-backed currency there.

In any case Mobutu is considered too much a prisoner of his entourage - especially his uncle Litho - to reduce the slush fund. Economists estimate the fund swallows up to a third of the country's estimated foreign exchange earnings of $1.25 billion to $1.35 billion.

At this point it is unclear whether the IMF team is empowered to reduce the corruption. Diplomats doubt Mobutu can rein in his entourage even if he wanted to.

Zaire's medium-and-long-term salvation can only be assured if the country accepts conditions reinstating its IMF standby facility status.

That would pave the way for a consortium of private banks to release $220 million in long-promised loans to help pay off foreign debts estimated at between $2 billion and $3 billion.

As of June 1 Zaire was believed $110 million in arrears on principal and interest.

The telltale sign of Western concern at the Brussels conference was the decision to rush food and medicine to Zaire.

Some Western diplomats believe top priority in Kinshasa, where half the 2.5 million population is believed unemployed and living on the border line. "It's too late to do much things for the interior anywhere," a diplomat said.

Serious droughts in this winter in key farming areas and an abnormally high rainfall in Shaba reduced food production although economists believe the harvest is less catastrophic than originally feared.

Western evaluations tend to vary, but the Belgians are thought most concerned for the very reason that they number some 18,000 here and account for more than half the foreigners in Zaire.

"I wake up in the middle of the night," one Belgian said, "and see a popular uprising directed against the whites because we are blamed for keeping Mobutu afloat.

"With 22 miles to the airport and hostile Cubans across the river in Brazzaville," he said, "if Kinshasa blows it will be 10, 20, 30 times worse than Kolwezi. Recent rumors of arms coming across the river from Brazzaville after dark in canoes don't make one feel any more secure."

Even less frightened observers are convinced that time is running out on Mobutu although they doubt a convulsion is imminent.

"The Zairians are inert and their passivity was proved when Mobutu after Kolwezi left Zaire for six days in Paris, Rabat and Dakar without even a grenade going off, a diplomat said. "Carried to the extreme you could argue that African dictators from Idi Amin in Uganda to Sexou Toure in Guinea have remained in power for years through sheer brutality."

Yet Zairian passivity in itself will not suffice for an explanation. The real problem start to work in order to persuade even more whites to come back and make even more things work," an economist said, "and for that you need security."

At most there are probably no more than 30,000 foreigners in Zaire, less than a third the number the Belgians had here to run what was then the richest colony in Africa.

"It, if, if," the economist added, "You keep adding one theoretical construction on another and in Zaire that is dangerous. At best it will take the IMF a year to begin to turn things around and even if the medicine cures the disease, the patient may be so weak he'll succumb anyhow."