NOME, ALASKA -- Last winter, Jim Stimpfle launched a four-foot weather balloon loaded with gum, tobacco and friendly messages toward the Siberian shore. The balloon hit the sea only three miles away, where Stimpfle's Eskimo friend Timothy Gologergen, out fishing, could rescue only the chewing tobacco.

After that first, comic misstep, Stimpfle, Gologergen and others on this dark, snowy peninsula have come a long way toward opening the U.S.-Siberian border, the back door to the Soviet Union.

The first research ship in 60 years to visit both sides of the Bering Strait has docked here. Letters and gifts have been exchanged between U.S. and Siberian villagers. An American woman has swum across the border for the first time, and Siberian and Alaskan scientists have signed a pact to study the impact of the Arctic climate on the human body and behavior.

At the same time, however, the Soviet and American navies have stepped up their maneuvers in the area, and the U.S. Air Force has intercepted nearly twice the usual number of Soviet aircraft, a sign that the chilly waters where the United States and the Soviet Union meet have become increasingly volatile.

Now, with a suddenness that has created white-hot excitement on Nome's frozen, 20-degrees-below-zero streets, proposals for local flights across the border have been placed on the agenda for the Reagan-Gorbachev summit this week.

Last week, KNOM-AM, the tiny radio station that is based in this community of 3,500, treated the news as one of the biggest things since the 1899 gold rush. It carried live interviews from Washington with Sen. Frank Murkowski (R-Alaska), who had persuaded the White House to push the issue, and special broadcasts in Russian by recent Georgetown graduate Therese Horvath to inform the neighbors in Provideniya, Siberia.

Stimpfle, who has been goading the two superpowers from his little real estate and insurance office here, said he envisions a new cultural, scientific and commercial bridge across the strait as important as the land bridge that first brought mankind to this gateway to North America 36,000 years ago.

"People in Nome are getting their passports; Nome public school teachers and students are interested in exchanges," he told the Soviet Embassy in a letter last month. "Eskimo elders want to renew friendships and see relatives, community groups and leaders want to visit and discuss projects, trade and see tourism develop."

As chairman of the Nome Chamber of Commerce Committee for Cooperation, Commerce and Peace (CCCP), Stimpfle has lobbied for daily flights across the strait. Alaskans consider it absurd that American visitors to Siberia generally have been required to enter and exit the Soviet Union through Europe. Provideniya, which is called Plover on some maps and is near Nome's latitude on the Siberian coast, "is only 26 minutes away by jet," Stimpfle said.

"Or about four hours if you're rowing," added Gologergen, a retired school maintenance worker whose Savoonga people live on St. Lawrence Island.

Nome residents are asking for a sister city relationship with Provideniya. Lee Nunn, a director of the Alaska Power Authority, and others have proposed a link between Alaskan and Siberian electric power systems to help create a worldwide system, as suggested by the San Diego-based Global Energy Network. Leaders here are sponsoring a "get-your-passport" campaign in anticipation of eased border restrictions and a rush of visitors, Soviet and American, that could increase Nome's usual load of 10,000 annual tourists tenfold.

In this town of gold miners, fishermen and state employes pinned to the southern edge of the Seward Peninsula, all these plans are taken seriously. Nome, shortened from "No Name" during its birth as a 15-mile-long tent city for gold prospectors, looks in winter like a collection of multicolored warehouses and construction gear. It offers few scenic delights.

But the town attracts hunters and boasts the celebrated Iditarod dogsled race, and its proximity to Siberia creates, in the view of the residents, an enormous opportunity.

"Barrow has the oil fields, and Kotzebue has the Red Dog {zinc} mine," Stimpfle said. "What does Nome have? Location, location, location."

In Dr. Ted Mala's view, that accident of geography is the key to overcoming all the political and economic differences that separate Alaska and Siberia. Mala's father, an Eskimo film actor, met his refugee mother in Hollywood, and the half-Russian, half-Eskimo Anchorage physician and associate professor of health sciences has sought ways to link his two heritages.

About six years ago, he saw a way: combining the research efforts of American and Soviet scientists who have struggled separately with the mysteries of life in the Arctic.

Now secretary general of the International Union for Circumpolar Health, Mala this year parlayed a letter to Gorbachev and repeated visits to the Soviet Union into an agreement between the University of Alaska, Anchorage, and the Siberian branch of the Soviet Academy of Medical Sciences. They will share data on such questions as whether all Arctic natives have higher levels of an enzyme needed to metabolize alcohol, and what the effects are of the stress of living with the cold, darkness and confinement of the Arctic.

"On a clear day, we cannot only wave but also walk across the ice from Alaska into Soviet territory," Mala said. "We are linked to one another by culture, history, common indigenous origins, common problems as well as shared environment."

The Soviet scientists who visited Alaska last month to sign the agreement were welcomed as heroes. In Nome, they were entertained by two troupes of native dancers. They handed out scores of little red star-shaped Lenin pins and consented to a dizzying airplane ride over Big Diomede, a Soviet island, and Little Diomede, a U.S. island, which together frame the narrowest part of the Bering Strait.

The U.S. and Soviet scientists have agreed not to seek military funds for their research, as the area continues to draw attention from strategic planners on both sides. The U.S. Navy, noting Soviet expansion in the northern Pacific, has conducted two major exercises by carrier task forces near the Aleutian Islands in the past year. It is building a $92 million radar system on Amchitka Island in that chain.

The U.S. Army 6th Division (Light) is adding troops monthly in Anchorage and Fairbanks, and the Air Force has added a tactical fighter squadron at Elmendorf Air Force Base, making a total of 33 F15s in the state, including many new models with improved range and power.

Air Force Sgt. Lloyd Tilmon, a spokesman for the 21st Tactical Fighter Wing at Elmendorf, said the Soviet air force has shown "an extremely significant increase" in activity in the area. U.S. F15s have scrambled 29 times this year to intercept 53 Soviet aircraft, including 45 bombers capable of carrying nuclear-tipped cruise missiles, as they approached the Alaskan coast.

This compares with 17 interceptions of 34 aircraft, including 32 bombers, in 1986 and only five interceptions of nine aircraft in 1983.

The journal Defense Week reported in September the discovery of Soviet military equipment on St. Lawrence Island, a U.S. territory off the Soviet coast. Maj. Fred Haynes of the Alaska Army National Guard here said similar equipment, such as gas masks and clothing with Soviet army patches, has been found on the island in past years. He said it has never been clear if they were left by covert Soviet visitors or just washed ashore from Siberia.

Most Alaskans, including those supporting closer ties with the Soviets, say they support a strong U.S. military presence. "But if we don't balance it out" with efforts to improve relations, Mala said, "the potential for the region to become a closed military zone is very strong."

The crew of the Surveyor, a National Oceanic and Atmospheric Administration ship, received a different impression from its stops at Provideniya and Nome this fall. They presented pictures and handicrafts from Nome to the Soviets, and similar gifts from Provideniya to the Americans here. Dancers entertained them on both shores. Their videos of the Siberian performance fascinated the American Eskimos, who saw many similarities with their dance style.

There was also a great deal of frantic merriment during Lynne Cox's 2.7-mile, two-hour swim in August between the two Diomede islands. When, at the last minute, the Soviets approved the crossing, several local residents, including Stimpfle, piled into seven additional boats in hopes of following Cox and her handlers into Soviet territory. Soviet military personnel let her crew pass but waved the others off.

Nonetheless, Stimpfle said, the trip was not a total loss. While trying to turn back, his boat became lost in a thick fog and almost ran into Big Diomede, the Soviet island they were told to avoid. "We almost made it," he said, "without even trying."

Special correspondent Hal Bernton contributed to this report.