Accusations continue to fly over claims of so-called dirty bombs being used in the Russia-Ukraine conflict.
Russia says it'll take to the UN security council its claim Ukraine is preparing to use such a weapon on its own soil, without offering any evidence.
UN nuclear watchdog inspectors will return to two sites in Ukraine at the centre of Russia's claims, on Kyiv's request.
Washington nuclear materials security program the Nuclear Threat Initiative vice-president Scott Roecker spoke to Māni Dunlop.
