Almost eight months after an Okinawa woman was allegedly slain by a civilian employee of a U.S. military base, Tokyo and Washington have effectively agreed to sign a supplementary treaty narrowing the scope of protection afforded to such workers by the Status of Forces Agreement.

Foreign Minister Fumio Kishida said Monday that the new system will contribute to preventing crimes committed by members of the so-called civilian component protected by SOFA. Tokyo and Washington will review the kinds of workers at U.S. bases who are covered by the pact, and determine in a timely fashion whether individual workers qualify for the “civilian component” designation.

Kishida also said Japan hopes to ink the deal before President Barack Obama leaves office next month.

“This agreement signifies the two allies can produce a visible outcome if we cooperate together,” Kishida said. “This will further move forward the Japan-U.S. alliance.”

The supplementary treaty was negotiated in response to the death of Rina Shimabukuro, 20, who was allegedly raped and murdered by Kenneth Franklin Shinzato, a civilian employee at Kadena Air Base in Okinawa and a former U.S. Marine.

The two countries have been in talks since agreeing in July to narrow the scope of workers who can be considered to be part of the civilian component.

The incident, which evoked memories of the 1995 rape of a 12-year-old girl by three U.S. service members, fueled anger among people in Okinawa, who have long been enraged by what they perceive to be the unfair nature of SOFA. Massive local protests erupted after Shimabukuro’s death, with participants demanding a withdrawal of the U.S. military from Okinawa.

The U.S. military currently has 7,000 civilian component workers in Japan. Both countries agreed that the new definition should exclude workers like Shinzato, who was engaged in simple computer-related work. Yet Kishida said it is unclear to what degree a reduction in the numbers of civilian component workers will be achieved, as the two sides are still working out the agreement’s details.

By signing a supplementary treaty, the government wants to make it look like it has achieved a more stringent system to reduce crimes by U.S. military base workers without revising SOFA itself.

The efficacy of the new system is unknown. The 1995 murder and rape case led to enhanced implementation of SOFA, which gives the U.S. military primary jurisdiction under certain circumstances. But base workers have continued to commit crimes, and the ratio of felonies committed by the civilian component is only a fraction of those committed by U.S. service members in general.

The announcement also came one day before Prime Minister Shinzo Abe was to make a historic trip to Pearl Harbor, following Obama’s visit to Hiroshima in May as the first sitting U.S. president to do so.

Kishida said the two leaders will emphasize the evolution of the alliance during Abe’s visit to Hawaii, where the two leaders are scheduled to hold their last summit.

Saddled with numerous issues in Okinawa, the government is apparently eager to settle this issue while Obama is still in office, due to looming uncertainties over the future of the Japan-U.S. alliance under President-elect Donald Trump.

Trump has said that Japan should pay more to shelter under the security umbrella provided by the U.S. military. While some experts in Okinawa said that Trump’s presidency could allow the two countries to review the meaning of the U.S. bases in Japan, his appointment of retired Gen. James Mattis as secretary of defense could indicate that Okinawa and the U.S. military won’t have an easy relationship where base issues are concerned.