The United States is pressing Japan to back a U.N. Security Council resolution that would impose an arms embargo on South Sudan, according to diplomats.

Japanese support is important if the resolution is to reach the minimum threshold of nine votes needed for passage in the Security Council, but Japan is concerned that the South Sudanese government could retaliate against U.N. representatives on the ground, including Japanese peacekeepers stationed there.

The resolution is unlikely to be vetoed by either Russia or China, putting the focus on how nonpermanent council members, including Japan, Senegal, Malaysia and Angola, will vote, a diplomatic source said.