A Chinese Navy admiral and honor guard welcomed the U.S. Navy back to China today for the first time in nearly four decades on a port call intended to improve U.S.-Chinese relations.

In contrast with the freewheeling American sailors and marines who largely ran Qingdao immediately after World War II, the Americans who roamed the city today were well briefed on Chinese sensitivities. Many of the more than 900 sailors who arrived aboard three ships carried a 32-page booklet issued by the Navy that admonished them not to pursue Chinese women or drink too much of the city's renowned Tsingtao beer, sold around the world under the old spelling of the city's name.

"It's a communist country, and we're ambassadors," said William Clack of Cincinnati, an electronic warfare specialist on the guided-missile cruiser USS Reeves.

Some sailors found the experience exciting and others confining. But most agreed that this was an unusually quiet shore leave. For one thing, Qingdao has no night life to speak of, except for a few restaurants kept open later than usual.

Elsewhere, said Clack, "you can basically get wild. Not here . . . . We're making history." Along with the Reeves, the destroyer USS Oldendorf and guided-missile frigate USS Rentz arrived in Qingdao to be greeted by Adm. Ma Xinchun, commander of China's North Sea Fleet.

Adm. James (Ace) Lyons, commander-in-chief of the U.S. Pacific Fleet, who came aboard the Reeves, told reporters that the week-long port call would promote further military cooperation between the United States and China.

With the aim of helping to modernize China's antiquated military equipment, the United States has made several limited weapons sales to China. The biggest to date, signed by Peking this week, calls for the United States to provide more than $ 500 million worth of electronic equipment for 50 of China's F8 interceptor jets.

The contrast between U.S. and Chinese equipment was evident today when the three U.S. ships steamed up to a pier with a Navy band aboard the Reeves playing "Happy Days Are Here Again."

The towering American ships, adorned with the latest naval missiles, radar, telecommunications gear and other electronic gadgetry, docked directly opposite three squat Chinese host ships -- a destroyer, frigate and submarine. U.S. Navy officers said that although the Soviet-style ships were constructed within the last decade, their technology dated from the 1950s and early '60s.

With little more to show the Americans than their pride, the Chinese insisted that the Americans hoist their signal flags to match the flags already decorating the Chinese ships. Getting the U.S. signal flags up delayed the welcoming ceremony more than 1 1/2 hours, but Lyons said the Americans were grateful for being given time to "full dress" their ships.

Citizens of Qingdao gathered to gawk at the American sailors at scenic points where tour buses deposited them. City officials had ordered workers to give the streets an extra cleaning before the arrival of the Americans. Work units throughout the city briefed residents on the port call and its justification -- improving U.S.-China relations.

The Rev. Stephan Wang, pastor of a government-authorized Protestant church here, said that some factories had to do extra propaganda work to convince older workers that the port visit was necessary.

Wang said that some U.S. sailors and marines had left an extremely bad impression after arriving in 1945 to accept the surrender of Japanese troops at the end of World War II.

The last U.S. ship stationed at Qingdao, the repair vessel USS Dixie, left on May 24, 1949, just before communist troops entered the city.

"Old people still remember that after drinking, the sailors would sometimes beat people up," Wang said. "They took liberties with women. Sometimes they raped women."

"But not all of them were bad," the pastor added. "Many of them behaved well. . . . . If the American sailors behave well this time, it will completely reverse the old memory."

Gilbert Luna of Los Angeles, a former U.S. Navy storekeeper who worked here in 1946-47, came back at his own expense to witness today's return of the Navy to Qingdao. Now in his late fifties, Luna, who came to China as an 18-year-old, said that when he served here the Americans controlled the port. "It was our little fiefdom," he said.

Luna recalled the city's rowdy night life with fondness but described its citizens then as "desperate people." He said many women, lacking any means of support, were driven into prostitution.

Today, Qingdao has its dark side -- a grim and polluted industrial zone -- as well as its beautiful beachfront, with sturdy stone villas left from the turn of the century when Germans occupied the city.

Liu Lichang, 66, a retired railroad worker, said he was willing to forget the times when foreigners came "only to extract benefits from China and not to help."

Dong Ziyang, a former rickshaw driver who worked first in a Japanese textile mill and then for American sailors, said that the Americans were brutal when they drank too much, but that working for the Japanese was "like living in hell."

Tang Tingxin, 39, an electrical technician who once commanded a Chinese Navy coastal patrol boat, stood outside the entrance to the naval base and pier where the American ships came in, hoping to meet one of the Americans. But the sailors, leaving the base in buses, passed by Tang and about 400 other Chinese onlookers.

Tang said that the arrival of the Americans was "a great event for my country . . . . "

"Even with the bad memories, we can't forget what the Americans did in the Pacific in World War II," he said, referring to the American role in defeating Japan.