Russia on Monday defended its veto of a U.N. resolution urging all nations to prevent a nuclear arms race in outer space, challenging the U.S., Japan and their Western allies to support Moscow’s rival resolution calling for a ban on all weapons in space “for all time.

Russia on Wednesday vetoed a U.S.-drafted United Nations Security Council resolution that called on countries to prevent an arms race in outer space, a move that prompted the United States to question if Moscow was hiding something.

Russia has vetoed a resolution at the UN Security Council calling on all countries to prevent an arms race in outer space. The draft resolution, put forward by the US and Japan, sought to reaffirm a principle already set out in the 1967 Outer Space Treaty.