O K I N A W A C I T Y, Japan, July 21, 2000 -- Tens of thousands of protesters formed a chain around a major U.S. air base today in a show of opposition to the American military presence in Japan.

The demonstration, timed to coincide with President Clinton’s visit to this weekend’s Group of Eight summit in Okinawa, taps into what U.S. military sources call a wave of anti-American sentiment across East Asia.

Clinton arrived early this morning at U.S. Kadena air base, the largest U.S. air base in Asia. He plans to leave the summit early Saturday, E.T., to arrive in Washington late Saturday to rejoin the Camp David talks by Sunday, ABCNews.com learned today.

At the Cornerstone of Peace, a memorial to the American, Japanese and Korean soldiers who died in World War II on the beaches of Okinawa, Clinton sought to soothe the tensions over the U.S. military presence on Okinawa. “We take seriously our responsibility to be good neighbors,” he said, “ and it is unacceptable to the United States when we do not meet that responsibility.”

He pledged to complete a process of consolidating U.S. bases on Okinawa and “to reduce our footprint on this island.”

U.S. bases take up about 20 percent of the island of Okinawa, with 30,000 troops stationed there.

There was no independent confirmation of the protesters’ numbers, but the demonstration appeared to be one of the largest anti-base protests in years. The human chain stretched for 11 miles around the air base. Organizers claimed to have mobilized more than 25,000 people for the chain — almost as many as the U.S. servicemen and -women on Okinawa.

In several areas, the protesters stood three or four deep. Many wore headbands with anti-base slogans and came with their children. “As teachers, we have vowed never to send our students to war again,” said Isao Kaneshiro, head of a local teachers’ union. “I want President Clinton to know that we don’t want his troops here.”

The protest, organized by local labor unions and civic groups, was peaceful, and there were no reports of arrests or incidents.

U.S. Military on Alert

The U.S. Armed Services have taken security precautions across the Pacific region, imposing a curfew for troops on Okinawa and warning servicemen elsewhere to keep a low profile and avoid trouble.

U.S. officials have also been warned by the Japanese government to expect “symbolic” terrorist attacks by protestors during the summit. Some 22,000 police, most flown in from other parts of Japan, have been deployed on Okinawa.

Senior U.S. officials have been urging caution. “During these times when there are fundamental changes under way, there are likely to be political sentiments expressed, and we just have to be cautious about them,” said Defense Secretary William Cohen, traveling in Australia last week.

Pentagon spokesman Kenneth Bacon conceded there are pockets of resistance in Okinawa, but said, “the majority of people in Japan and Korea want U.S. troops to stay as a stabilizing influence.”

But Admiral Dennis Blair, commander in chief of all U.S. forces in the Pacific was more blunt. “We haven’t buttoned up bases or any of that, but we still told people to watch out for each other, to be more careful because there’s more disturbances in the area and some prudent measures are being taken.”

A Turbulent History

Clinton is the first American president to visit Okinawa. Following Japan’s surrender in World War II, Washington governed Okinawa until 1972 — 20 years after the occupation of the rest of Japan had ended.

The United States has continued to use Okinawa as a major military outpost in the Pacific, however.

Nearly 30,000 of the 47,000 U.S. troops in Japan are stationed on Okinawa, including the largest contingent of Marines outside the United States. Many Okinawans feel the presence is too heavy, and want it reduced or eliminated.

Okinawa’s residents have objected for years to the military base. Tensions mounted when, on July 3, a 19-year-old U.S. Marine was accused of molesting a young girl after he allegedly broke into her house in drunken stupor. In another incident, a U.S. Air Force serviceman was arrested on suspicion he left the scene of an accident after the car he was driving hit a pedestrian.

Regional Rumbles

Following the recent North -South Korea summit, public discontent over U.S. military presence in the entire Pacific region has exacerbated. In Seoul, anti-American protests broke out after the U.S. military dumped 20 gallons of formaldehyde in the local wastewater sewage system. U.S. officials say they don’t believe they harmed the environment but they are investigating how the illegal dumping occurred.

In the last month, crimes against U.S. personnel in Seoul’s Itaewon shopping district included the stabbing death of an Army doctor. In three separate incidents, U.S. military and civilians were attacked by Koreans. U.S. military officials in South Korea are responding to local unrest, issuing new warnings to troops to be careful.

The Show Goes on

Meanwhile, talks between world leaders have begun. German Chancellor Gerhard Schroeder was the first leader to arrive, and Russian President Vladimir Putin, who arrived late this afternoon, was the last.

Several leaders held bilateral meetings in Tokyo before flying on to Okinawa. Clinton was to hold a meeting with Japan’s Prime Minister Yoshiro Mori today, but postponed that at the last minute to finish the Mideast peace talks being held at Camp David in the United States. (See related story).

U.S. Treasury Secretary Lawrence Summers stood in for Clinton Thursday in Tokyo at pre-G-8 meeting with developing countries. He was accompanied by Gene Sperling, the national economic adviser, and Lael Brainard, deputy national economic adviser.

The G-8 consists of the United States, Japan, Russia, Britain, Italy, Canada, Germany and France. The group has held summits each year for the past 25 years.

This year’s summit was expected to focus on information technology and ways to alleviate the “digital divide, the gap in access to technology between developed and developing countries ” money laundering and financial crimes, debt relief for the world’s poorest nations and the global economy in general.

But the summit was also expected to be heavy on the photo-op.

The meetings are being held in the city of Nago, on the northern part of Okinawa, and officials are hoping it will put Okinawa on the international tourism map. Tourism is Okinawa’s most important source of income after the military bases.

Among the main activities planned for the leaders is a dinner and traditional dancing at Okinawa’s Shuri Castle, a remnant of the Okinawan dynasty that ruled these islands as a kingdom independent from Japan for nearly three centuries until it was assimilated in the late 1800s.

ABCNews' Tamara Lipper in Okinawa, Barbara Starr in Washington and The Associated Press and Reuters contributed to this report.