BBC News, New York
Western concerns about Iran's nuclear programme have so far dominated the latest UN conference on the treaty aimed at stopping the spread and stockpiling of nuclear weapons.
But another state is sharing centre stage at the month-long negotiations in New York to strengthen the Nuclear Non-Proliferation Treaty (NPT), despite its complete absence from the hall.
"Israel's nuclear arsenal stands like the radioactive elephant in the room," says blogger and journalist Khaled Diab.
Israel is widely believed to have between 100 and 200 nuclear warheads. Yet it has never declared them, signed on to the NPT, or opened its nuclear facilities to inspection.
Calls from NPT podiums for it to do all three are common enough. But with the US homing in on the potential proliferation risk posed by Iran, Arab and Islamic states have raised the volume on the threat they say is posed by Israel's actual nuclear arsenal.
Crucially, the debate has galvanised long-standing demands for a nuclear-weapons-free zone in the Middle East.