Bush administration officials with access to U.S. intelligence reports say they believe there is little chance that the internationally supported economic sanctions against Iraq will weaken the country enough to compel it to surrender Kuwait before next spring, if then.

Although the trade embargo has shut off virtually all trade with Iraq in the past three months, it has had no appreciable effect so far on Iraqi military capabilities or Iraqi President Saddam Hussein's resolve to hold onto Kuwait, several government analysts and officials said in interviews.

"The bottom line on the sanctions is, when does it cause Saddam enough heartburn to decide he's had enough," one official said this week. "We don't see that happening any time soon." To predict the sanctions might bite deeply enough by springtime, he added, would be optimistic. "It could be next fall."

The latest intelligence reports represent a lengthening of some earlier assessments about how quickly the sanctions would take effect and how much economic disruption and discomfort the Iraqis are willing to endure before giving in.

This has complicated U.S. decision-making on the Middle East crisis because senior officials would prefer to let the sanctions work and avoid war. At the same time, the Bush administration does not want to be drawn into a protracted crisis with unpredictable domestic political consequences.

The issue of how quickly the economic sanctions can work also is at the root of recent tensions between the executive branch and Congress over the administration's decision two weeks ago to add nearly 200,000 troops to the U.S. force of more than 230,000 already in the Middle East.

Senior U.S. officials have described the additional deployments as laying the groundwork for an offensive military operation that may occur in the first three months of 1991.

As the intelligence assessments have circulated, some White House and State Department officials who two months ago said the international embargo was "working" and would force Iraq to withdraw from Kuwait, have shifted their public predictions of its success. Now, they say, the cutoff of trade may not work or may take so long that the U.S.-led coalition opposed to Iraq could crumble.

"Many major countries around the world anticipated at the beginning of this that sanctions would work inside of 3 1/2 months," Secretary of State James A. Baker III said last Sunday on ABC television. "Yes, we should give them additional time. . . . But it's very hard to put a finite amount of time on that."

President Bush, who predicted in August that the "economic sanctions should begin to bite pretty soon," said last week the United States was now receiving "different reports from countries near to Iraq" about the effectiveness of the sanctions.

He told interviewers on Cable News Network, "I can't give you and the American people a total assessment of that question."

Many had been optimistic that sanctions would be effective because Iraq's economy depends heavily on foreign trade. Revenues from exported oil have provided nearly half the national income, according to Western analysts. Food imports have accounted for about 70 percent of food consumed in years of good rainfall, 80 percent in dry years, according to the U.S. Department of Agriculture.

Many manufactured goods in Iraq, from vehicles to electrical accessories, have come from abroad, and many heavy industrial plants have relied on imported parts.

Several officials and government analysts said that while the sanctions have achieved some "technical" success by halting significant Iraqi imports or exports of commercial and industrial goods, the cutoff has clearly failed to bring about any political change in Iraqi policies.

Iraq's announcement this week that an additional 200,000 troops would be deployed in and near Kuwait, on top of the 430,000 already there, is considered the latest sign that Saddam is determined not to flinch.

Most of Iraq's development projects have "ground to a halt," one analyst reported. "There are some shortages of raw materials such as lubricants and chemicals. Industrial output has declined by roughly 40 percent. The range of available food is steadily deterioriating. Military factories are operating below their capacity."

Some air-defense radars and other military equipment have been idled to avoid unnecessary wear and tear, another analyst said.

But there has been no significant decline observed in Iraqi military training, ground exercises or patrols by military aircraft.

"You can look at the sanctions as a glass half empty or half full," an administration official said. "Shipping is way down. Truck fleets are idle. Airlines aren't flying into Baghdad any more. But smuggling is endemic -- across Jordan, through Turkey and more and more is coming in through Iran."

Saddam has enough gasoline and basic necessities to keep going for months without changing course, an official said. "He certainly has enough food to make it through the winter," another official said.

Several experts said they agree that the sanctions are unlikely before next spring or summer to force Saddam's hand by, for example, causing dissent among his top advisers or among influential sectors of Iraqi society.

One administration official familiar with the intelligence reports said yesterday that there is no evidence of any revolt or coup attempt against Saddam within the Iraqi military since the invasion of Kuwait.

He noted that the elite Republican Guards military forces are deployed in southern Iraq relatively far from Saddam's headquarters, further indicating that the Iraqi leader feels safe from internal attack.

"One would have to give these measures at least a year to prove they had failed," said Gary Hufbauer, a Georgetown University economics professor and co-author of a new book on the operation of economic sanctions. "This is not a quick surgical approach. It really is a different ballgame and must be appreciated for that."

Hufbauer's study of 115 episodes involving economic sanctions since World War I found only a few instances of success in less than one to two years.

"The median period was four to five years," he said. "Over the entire period, sanctions were effective in one-third of the cases, although in recent years, only one quarter were able to achieve their objectives.

"I predict sanctions will work in Iraq, although 'success' will fall short of an all-out victory involving a complete Iraqi withdrawal and the surrender of Iraq's weapons of mass destruction," said Hufbauer, a visiting fellow at the Institute for International Economics in Washington. "You don't often get a grand slam with sanctions."

Patrick Clawson, a resident scholar at the Foreign Policy Research Institute who formerly served as an Iraqi specialist for the International Monetary Fund, predicts that the sanctions may not work before the end of 1991. "Iraq's industries are not that vital to the economy," he said. "Food shortages do not necessarily lead to popular discontent if the population supports {the notion of} a national emergency."

The Senate Foreign Relations Committee, whose chairman, Claiborne Pell (D-R.I.), has said he prefers to defer any military conflict, announced that its hearings on the administration's policies beginning on Dec. 4 "will focus on the foreign policy justification for not waiting for the economic embargo to force Iraq out of Kuwait."

Sen. Sam Nunn (D-Ga.), who will chair Armed Services Committee hearings expected to begin next week, said Wednesday on NBC television, "I'd like to see a little more analysis and concentration done on whether the embargo is going to work and when it's going to work. I happen to believe that when you cut off 98 percent of the income of a country, eventually it's going to work if you give it time.

"So I would counsel patience now," Nunn said. "We ought to start behaving as if time is on our side rather than on Iraq's side, and I think that would be an accurate portrayal."

Gen. Alfred M. Gray Jr., Marine Corps commandant and member of the Joint Chiefs of Staff, expressed the same view in a speech in Washington Wednesday. "I keep saying, what's the hurry here? Time is on our side . . . not Saddam's," Gray told military contractors and retired Marines.

Gray, who two weeks ago cautioned against any U.S. attack before the military could open bottlenecks in the system for supplying U.S. forces in Saudi Arabia, said of the economic embargo that "we ought to let this thing unfold and stay behind it." Several senior military officials said many other officers were sympathetic to Gray's desire to wait longer for sanctions to work.