Japan and the United States on Monday signed a new pact allowing local officials to enter U.S. military bases in Japan to conduct environmental surveys.

Under the accord, the U.S. can also give permission for Japan to conduct soil and other relevant surveys about seven months prior to the expected return to Japanese control of land used for U.S. bases.

The agreement was signed between Foreign Minister Fumio Kishida and U.S. Defense Secretary Ash Carter when they met Monday during Kishida’s five-day trip to the U.S. that started in Washington.

It is the first time a pact of this kind, which supplements the existing Japan-U.S. Status of Forces Agreement governing the use of U.S. bases in Japan, has been drawn up, a senior Foreign Ministry official said.

The agreement came into effect immediately.

Kishida said at the signing ceremony that the environmental pact “has great significance and will enhance local communities’ trust” in the management of U.S. military bases in Japan.

“We are mindful about being good neighbors, which includes realigning our bases and being aware of any concerns that local communities might have about our operations,” Carter said.

The agreement “represents a big step forward in our alliance,” he added.

The preexisting SOFA had no clause allowing municipalities to conduct environmental surveys on the bases, thereby requiring prefectural and municipal officials to obtain U.S. permission to enter facilities.

The new deal, which covers all municipalities hosting U.S. bases in Japan, is part of what the central government sees as measures to ease the base-hosting burden of these municipalities, particularly in Okinawa Prefecture.

The government is hoping that taking such a step will help move forward a controversial plan, being pushed by the central government and U.S., for the U.S. Marine Corps Air Station Futenma to relocate within Okinawa, Japanese officials said.

The relocation plan remains a source of tension between the central and local governments, with local authorities and communities in Okinawa demanding that the base be moved outside of the southern island prefecture, which hosts the bulk of U.S. military forces in Japan.

Okinawa and other base-hosting prefectures have long been asking for such environmental surveys, fearing possible pollution and requesting that surveys be carried out long before land is returned so that they can plan ahead for how to use it, the officials said.

But whether the new accord will satisfy Okinawa and other communities hosting U.S. bases remains to be seen amid their demands that environmental surveys be carried out three years before the return of land.

Last October, Japan and the U.S. reached a “substantial agreement” on the pact but details as to the extent to which Japan would be ensured the right of access to U.S. facilities were not decided.

The new agreement addresses the establishment and maintenance of procedures for Japanese authorities to have appropriate access to U.S. facilities and areas in two cases.

One is when an environmental or spill incident occurs within a base, while the other is when field surveys, including cultural asset surveys, are needed for land expected to be returned to Japanese control.

When an incident occurs, Japan can request on-site inspections and ask for samples of soil and water believed to be contaminated. The U.S. will then promptly respond to the request under the deal.

The new pact also says the Japanese and U.S. governments will share available and appropriate information, and that the U.S. will continue to abide by the Japan Environmental Governing Standards.

Conducting environmental surveys for land expected to be returned can also be done earlier than the time frame of 150 days, should Tokyo and Washington reach a separate agreement, the ministry official said.

Japan and the U.S. decided to drop a section under which Japan would pay for the costs of environmental protection projects, as agreed last October, the official said.