Barringa last minute change in plans, orders will be cut for a small detachment of U.S. Marines to make an amphibious landing in northern Saudi Arabia close to the Kuwaiti border later this month, part of a war-of-nerves testing of Saddam Hussein's intentions.

The landing could be billed as a "minor provocation," an official aware of the plans said privately. "Let's see what Saddam does," he added. The Iraqi strongman-dictator might do nothing. On the other hand, if he construes the operation as a first step to something more, he might do a great deal -- perhaps fire one of his Chinese-built Silkworm missiles to stop a threatened invasion.

Whatever the Iraqi reaction, President Bush's purpose is clear: to ratchet up the pressure and raise the odds of war in Saddam's calculation. That's what he did with his decision Thursday to send about 200,000 assault troops to the Gulf.

If the case of Saddam vs. the world is to be ended without war, Bush's threats must be credible. To make them so, he is using all the military, political and diplomatic weapons he can find. He cannot say so, but the ultimate aim looks like a negotiated settlement. "It is important to be intentionally provocative on occasion," a U.S. official told us.

In this climate, such high-risk military games as a Marine amphibious landing tests the political and psychological reflexes of one of the world's roughest, most resilient leaders. This learning process for Bush justifies the grim face-off that will soon see nearly one-half of America's entire military might (except for nuclear weaponry) pitted against the half million combat-ready troops of a small Arab state headed by a dangerous adventurer.

Saddam Hussein is doing his own testing. He has sent Iraqi warplanes on at least one dangerous pass violating several miles of Saudi airspace, an act neither he nor the United States has admitted. Pentagon officials also say privately that small detachments of his troops have at least once penetrated Saudi territory to about 5 kilometers. Again, there was no announcement.

Behind these mutual provocations is the threat of carnage. The United States is now making elaborate preparations for care of the wounded, readying about 20 Army hospitals in Europe, keeping two hospital ships on permanent station in the Gulf and putting up new field hospitals in Saudi Arabia.

Saddam is well aware of this, and it may signal him that Bush means what he says about waging war if necessary to force him out of Kuwait. Nobody can be sure. Whatever his impact on the Iraqi strongman, the American president has enjoyed conspicuous success in keeping his coalition together despite internal stresses.

When Israel spooked the administration into giving it more than $1 billion in new military, oil-storage and other assistance as an offset for huge arms sales to Saudi Arabia, Syrian President Hafez Assad sent a blunt message to the White House that he would not tolerate it. His government warned that just as Syria had been vital to Bush in building Arab support against Iraq, it could also destroy it. Syrian troops bound for the Gulf were put on hold.

Within 10 days, Bush had quietly arranged for a cool $1 billion payoff to Damascus to keep it in the fold and its troops going to Saudi Arabia. Although the cash presumably came from Saudi oil, George Bush was the deal maker.

But he also needs an additional piece of vital evidence to make Saddam believe that Iraq faces all-out war unless it withdraws from Kuwait. Bush wants his coalition partners to do the unprecedented: turn over to him the sole power of attorney to make the war decision for them. That is what Secretary of State James A. Baker III spent the past week trying to line up in a half dozen capitals.

If Bush can pull this off, it might conceivably put enough pressure on Saddam to bring him to a diplomatic settlement behind the scenes with the Soviets, the French and the Arabs. A misstep at any point along the way, such as Iraqi retaliation when the Marines pull off their amphibious landing, could bring war overnight. For three months, however, no such misstep has occurred.

Publicly, Bush swears he will not consider talks until Saddam is out of Kuwait "without conditions." But given the calculating way he has been tightening the screws on Iraq, there is growing belief here in his own administration that the president will negotiate if a credible threat of war frightens Saddam back from the brink.