TOKYO (AP) _ Tadahiko Okumura explains the project with the pride of an engineer and the savvy of a salesman: A 2,470-acre heliport off the shores of Okinawa that can keep U.S. Marines safe through even the strongest typhoon.

The price _ a mere $2.2 billion dollars. Hangars not included.

Japanese corporations are jockeying furiously for what could be some very lucrative contracts as government negotiators put the finishing touches on a plan to make the nearly 30,000 U.S. troops on Okinawa less intrusive.

Many Okinawans, however, are beginning to worry they might end up being sold out.

The restructuring is the result of an intense re-examination of the U.S.-Japan security relationship after three GIs abducted and raped a 12-year-old girl in September 1995, sparking widespread anger in Okinawa.

Officials hope the final package _ to be made public Monday in Tokyo during the visit of U.S. Defense Secretary William Perry _ will help defuse islanders' longstanding opposition to the troop presence.

Many proposals already have been announced.

Along with noise-reduction measures and changes in some operating procedures, the plan will include the return of about 20 percent of the land used by the U.S. military, the biggest turnover in decades.

About a fifth of Okinawa Island is reserved for use by the United States, which has 47,000 troops in Japan under a mutual security treaty.

The most important facility to be returned is Futenma Air Station, a key Marine heliport where 100 aircraft and 4,000 troops are based.

Located in a heavily populated area, the heliport long has been a major source of friction, and the announcement of its return was widely praised.

Other items on the list are a military port, communications sites and an auxiliary airfield. But the United States has insisted the facilities only will be returned if adequate replacements are built elsewhere to ensure that troops can maintain combat readiness.

Japan would foot the bill, and the construction could be a much-needed shot in the arm for Okinawa's economy, the weakest of any region in Japan.

Even so, local opposition to several proposed relocation sites for the air station has been intense.

``Instead of just moving it somewhere within Okinawa, it should be moved out of Okinawa,'' Mayor Tetsuya Higa of Nago, one of Okinawa's largest cities, wrote in a recent newspaper commentary.

He and several other mayors have vowed to lead protests if their cities are chosen.

With such opposition to on-land sites not expected to let up, Prime Minister Ryutaro Hashimoto this week said specifics on the heliport's future probably will be left out of the Monday announcement.

And though many Okinawan groups have expressed concern that locating the heliport offshore would wreak havoc on the undersea environment, some of Japan's largest corporations are jumping at the idea.

``We think it is the best solution all around,'' said engineer Okumura, who is coordinating plans for a consortium of 12 major construction, shipping and heavy industry interests.

Okumura said the consortium's idea for a platform supported by 6,000 steel pillars is similar to technology used in New York's La Guardia Airport and several smaller projects already completed in Japan.

Another company proposed building a floating platform that could be moved in time of crisis. Neither proposal has been formally submitted.

Consortium members say the offshore platform's effect on the environment would be minimal, but the economic payoff for Okinawan subcontractors significant.

``We realize how delicate the issue is to the people of Okinawa,'' said Jay Kondo, a spokesman for trading house Nissho Iwai, a consortium member.

``We believe the offshore option is the best,'' he said. ``But in the end it is a political decision.''