Two squads of U.S. paratroopers roared down onto the soccer field in their choppers, kicking up clouds of dust. The combat-equipped men hit the dry field running, then flopped prone into defensive positions, their rifles ready. Ahead of them, youths of the small seaside town of Gouyave, on Grenada's west coast, sat watching from a bridge railing. They broke into loud applause. So, too, did local women at the sides of the field. The American troops, who had been searching for armed Cuban or Grenadian hold outs in the little war that was over, had been given a bad tip. They stood up to return the waves of the villagers.

Three weeks after the Oct. 25 U.S. military invasion, life on the tiny island took on an Evelyn Waugh flavor. The week's only known military casualty was a paratrooper who hurt himself while body surfing. Marijuana sales resumed along Ganja Alley, a colorful corner of St. George's, and local businessmen had their first postinvasion Rotary Club luncheon. Even Gail Reed, the American-born wife of the Cuban ambassador, whose embassy had been ringed for days by U.S. troops, was able to joke before flying back to Havana: "I'm just sorry I left my Jane Fonda workout videotape at home."

Still, there was serious business to be done in Grenada. The last of the 634 Cuban prisoners were returned to their homeland. Tons of American construction supplies and equipment were flown to the island, where U.S. military engineers will supervise the rebuilding of roads, water systems and telephone and power facilities. Some $3.5 million in emergency U.S. funds had been allotted to the task, but the total seemed likely to fall far short of eventual needs.

Sir Paul Scoon, the once ceremonial representative of the British Queen in the Commonwealth nation, was running the island as Governor-General. With a British lawyer at his side, he announced the appointment of a nine-man "advisory council" that will help administer affairs in Grenada until a new government is elected, presumably under a democratic constitution. No one could say when that might be. The council, composed of nonpolitical Grenadians with administrative skills, is to be headed by Meredith Alister

McIntyre, 51, now deputy secretary-general of the U.N. Conference on Trade and Development in Geneva. Scoon gave high priority to forming "an efficient and effective police service free of politics." Police duties were being performed by troops from neighboring Caribbean nations, as well as by some 3,000 U.S. paratroopers still on the island.

In Washington, before leaving for the Far East, Ronald Reagan solidified the broad popular support for his decision to invade Grenada. He basked in the virtually unanimous praise of American students from St. George's University School of Medicine, whose perceived peril on Grenada had been one of the President's rationales for what he called the "rescue mission." Addressing about 300 of the returned students, whom he had invited to the White House, along with some of the troops who had helped them get off the chaotic island, Reagan criticized those who "belittled the danger that you were in." The President added: "It is very easy for some know-it-all in a plush protected quarter to say that you were in no danger. I have wondered how many of them would have changed places with you." The students' cheers rolled across the South Lawn.

 In another effort to shore up support for the invasion, the Administration placed captured Cuban weapons on display in a hangar at Andrews Air Force Base. The most formidable were two Soviet-built BTR-60 armored personnel carriers. Twelve of them had been spirited at night into Grenada 18 months ago by the Cubans, after electric power had been cut and roadblocks installed to conceal the unloading. Also on display were twelve ZU-23 antiaircraft guns, 291 submachine guns, 6,330 rifles and 5.6 million rounds of ammunition. The Pentagon termed the arms cache sufficient to equip two Cuban battalions (about 500 men each) for up to 45 days of combat.

A congressional study group concluded, after a three-day trip to Grenada, that Reagan's move had been justified. The 14 members of Congress, headed by Democrat Thomas Foley of Washington State, reported to House Speaker Tip O'Neill that most of them felt that the students had been possible targets for a Tehrantype taking of hostages. This caused O'Neill, who had denounced Reagan's decision, to reverse himself. Noting that "a potentially life-threatening situation existed on the island," the Speaker said that the invasion "was justified under these particular circumstances."

There were a few dissenters among the congressional fact finders. "Not a single American child nor single American national was in any way placed in danger or placed in a hostage situation prior to the invasion," insisted Ohio Democrat Louis Stokes. The Congressional Black Caucus denounced the intervention. Seven other Democratic Congressmen, led by Ted Weiss of New York, introduced a quixotic resolution to impeach Reagan for sending in the troops, which would, of course, go exactly nowhere. Just outside the White House on Saturday, a youngish crowd of at least 20,000 gathered to demonstrate their displeasure with the Grenada adventure and with U.S. military involvement in Central America.

But overall the Grenada operation seemed to produce a new public pride in the military. It infused Veterans Day observances last week, and was evident as Army Rangers and some of the paratroopers returned from the Caribbean. "It's great to feel wanted," Ranger Sergeant Tracy Hickman told one reporter at Georgia's Hunter Army Airfield, contrasting the bitter homecoming from Vietnam with last week's warm reception. A post-invasion poll taken by the Washington Post and ABC News showed that 63% of Americans approve the way Reagan is handling the presidency, the highest level in two years, and attributed his gain largely to the Grenada intervention.

While the Administration had gained wide public approval at home for its Grenada action, the question of how long the U.S. should maintain troops on the island was still open. The Administration had predicted quick withdrawal, stressing that the U.S. had no intention of occupying or imposing political decisions on the islanders. Defense Secretary Caspar Weinberger said he expected U.S. troops to be off the island by Christmas. Scoon and many Grenadians familiar with the island's factional politics warned the visiting Congressmen that U.S. forces should stay far longer to ensure stability.

An ironic problem for the Americans is that many of the Marxist-inspired social projects were welcomed by Grenadians, who now expect the U.S. to continue them with U.S. dollars. They include medical clinics, adult-education courses, scholarships for study abroad, housing assistance, an uncompleted new sports stadium and, of course, the controversial 10,000-ft. airstrip, which had been budgeted as a $71 million project. It is three-fourths completed.

One preliminary estimate of the cost of restoring Grenada's lagging economy and its basic physical facilities is $100 million. That is close to a third of the Administration's proposed spending for its entire Caribbean Basin Initiative. Concedes one U.S. Caribbean specialist: "Whatever we give here has to be matched in the neighboring island states. Otherwise they will draw the undesirable conclusion that the best way to receive U.S. aid is to turn Red and then be rescued."

While the Administration's Grenada venture had turned out a popular success, the Government's information apparatus was still in some disarray. Last week, for example, State Department Spokesman John Hughes officially confirmed a rumor that a grave holding more than 100 bodies of Grenadians slain by Marxist forces in the "bloody Wednesday" massacre of Oct. 19 had been found on the island. Next day he had to admit there was no such discovery. U.S. military authorities later located a grave believed to have held the burned bodies of former Prime Minister Maurice Bishop and three Cabinet members slain with him in the coup.
Confusion over casualty counts continued. Major General Norman Schwarzkopf, deputy commander of the invasion force, said that 160 Grenadian soldiers and 71 Cubans had been killed during the invasion. The Pentagon had given a much lower count of 59 Cuban and Grenadian combat deaths, offering no breakdown on the nationalities. There was agreement that 18 Americans had died.

The glaring lack of advance intelligence about Grenada and the haste with which the military was ordered to mount the invasion showed in the fact that the U.S. forces, as it turns out, were unaware that the medical students were located on two campuses, True Blue and Grand Anse, some four miles apart. The soldiers reached 130 True Blue students early on the invasion day. But it was not until 30 hours later, during which time a student ham-radio operator on Grand Anse kept listeners throughout the hemisphere informed that his campus was still cut off from U.S. forces, that Army Rangers finally rescued the 224 students there. For so successful an operation, it was clear there were still post-mortems to be conducted and lessons to be learned.

-By EdMagnuson. Reported by William McWhirter/St. George's and Chistopher Reánan/Washington