President Trump and Japanese Prime Minister Shinzo Abe have agreed to “dramatically expand” human spaceflight cooperation. Trump is in Japan on a four-day visit. He made the announcement at a joint press conference with Abe today.

Japan is already a partner in the International Space Station (ISS) and the two countries have been discussing cooperation in future human space exploration for many years. This is the first statement since the White House decided to accelerate NASA’s plan to return astronauts to the lunar surface by 2024, however.

Japan and other countries have been making plans to participate in the Gateway that will orbit the Moon and serve as a transfer point between the Earth and the lunar surface and, eventually, the Earth and Mars. There has been concern that the new plan, focused on Americans on the lunar surface, would leave international partners with a less prominent role. The announcement today shores up the international component.

On Saturday as Trump arrived in Japan, the White House put out a separate statement that included “cooperating to advance our shared interests in space, including accelerating NASA’s return to the Moon” as one of the areas of “Advancing Our Shared Prosperity.”

The details of what the two countries agreed to were not provided in the press conference and Abe did not mention space cooperation in his remarks. Japan has already expressed interest in providing a habitat for the Gateway and logistics support, however. An illustration of the Gateway configuration envisioned before the decision to focus on returning Americans to the surface by 2024 — now called Artemis — included a rendering of the proposed contribution by the Japan Aerospace Exploration Agency (JAXA), although no agreement had been signed at the time committing Japan to the program.

Japan became one of the original partners in the U.S.-led space station program, then called Freedom, in 1988. It provided one of the three science modules for what now is known as ISS. The Japanese Experiment Module (JEM) or Kibo (Hope) is a multipurpose module with both interior and exterior science research stations. It is perhaps best known as the deployment location for cubesats that are ejected via Kibo’s “back porch.” Japan also resupplies the ISS using its HTV cargo spacecraft, the largest of the vehicles that deliver equipment, supplies, and scientific experiments.

Canada is the only other country that has made a formal commitment to the Gateway program. It will provide Canadarm3, building on its experience with Canadarm, which it built for the space shuttle, and Canadarm2 for ISS.

NASA also is in discussions with its other ISS partners, Europe and Russia, and other nations on cooperation in human spaceflight exploration. Much of this work has been ongoing for years through the International Space Exploration Coordination Group (ISECG). The most recent ISECG “Global Exploration Roadmap” was released in January 2018 just before Japan hosted the second International Space Exploration Forum (ISEF-2).