President Trump has been talking with his aides about withdrawing from the Postwar Japan Defense Pact, a longstanding defense treaty with Japan that he believes is unfair to the U.S., Bloomberg News reports. Trump reportedly thinks the agreement is too one-sided because it promises U.S. aid to Japan if it is ever attacked, but doesn’t require any defense from Japan’s military if the U.S. is attacked. Trump has also told some of his aides that he regards Japan’s repeated efforts to move a large U.S. military base in Okinawa as a sort of land-grab and has raised the idea of seeking financial compensation for the relocation of American forces, according to Bloomberg. The president hasn’t made any official steps to pull out of the treaty, and it’s unclear if a president can pull out of a ratified treaty without congressional approval. Trump is set to travel to Japan on Wednesday for the Group of 20 summit in Osaka.