There is not yet a formal U.S. - China agreement on rare earths. In the Meantime, from Korea's Chosun Daily, November 25:
Responds to U.S. ties with Australia, South Korea to reduce Chinese rare earth reliance
China announced the launch of an international cooperation body related to mineral mining, including rare earths, with 19 developing countries. It has built a “supply chain alliance” by leveraging rare earths, its most powerful “external weapon.” There are interpretations that China, which has been using “rare earth export controls” as a lever against the U.S., is now moving to establish a solid bloc to counter the U.S. using rare earths.
According to the Chinese Ministry of Commerce on the 24th, Chinese Premier Li Qiang officially announced the “Green Minerals Global Economic and Trade Cooperation Initiative” at the G20 (20-country) summit held in Johannesburg, South Africa, the previous day. In his speech at the meeting, Li Chang stated, “We must promote mutually beneficial cooperation and peaceful use of major mineral industries,” and added, “We should optimize profit distribution at each stage of the industrial and supply chains and better protect the interests of developing countries.” He also emphasized, “We must carefully address the military use of minerals to prevent safety risks.”
The countries joining the initiative include 19 nations such as Cambodia, Nigeria, Myanmar, and Zimbabwe, as well as the United Nations Industrial Development Organization (UNIDO). The Chinese Ministry of Commerce stated that the goal of this initiative is to “stabilize mineral supply” and strengthen open, mutually beneficial, fair, and reasonable trade cooperation. To this end, it proposed seven areas of cooperation: creating a stable policy environment, liberalizing green trade, fulfilling social responsibilities, expanding beneficiary groups, deepening technological exchanges, strengthening investment cooperation, and deepening multilateral mechanisms. Specific details such as the scale of Chinese investment and implementation schedules were not disclosed....
....MUCH MORE (bolding in original)