score:4
It has been divided between Saudi Arabia and Iraq.
Saudi Arabia and Iraq had in fact reached an agreement on partitioning the Saudi-Iraqi Neutral Zone in 1981. This was ratified as a general border treaty in 1983. This created the de factor border depicted in the above map, as dashed lines. Notice it cuts through the Neutral Zone at the centre.
Tentative agreement on the partition of the Saudi-Iraqi neutral zone was reached in 1981, and partition was finalized by 1983.
Both sides promptly forgot to notify the world until 1991, when Saudi Arabia finally registered the treaty with the United Nations. The negotiated border became internationally recognised thereafter. As you can see in the 1993 map below, the neutral zone was divided up through the centre.
Maps are from the Perry-CastaΓ±eda Library Map Collection of the University of Texas Libraries.