Serbia says it is no longer on the list of potential targets of nuclear terrorism.
This after about 2500 kilogrammes of radioactive spent atomic fuel was sent from Serbia to Russia.
The shipment was carried out in secret under heavy security.
It was feared that in the wrong hands the material could have been used to make bombs.
The month-long operation was coordinated by the UN nuclear watchdog, the International Atomic Energy Agency.
IAEA Special Project Manager John Kelly said: “Serbia has now joined the group of countries which no longer has highly enriched uranium on their territories. Thank you for that.”
Uranium refined to high levels can be used to make atomic weapons.
The operation was the largest single shipment made under a multi-national programme to return nuclear material to the countries where it originally came from.
