NATO member state observers have expressed readiness to promote nuclear disarmament on the second day of the meeting on the UN nuclear weapons ban treaty.

The first meeting of States Parties to the Treaty on the Prohibition of Nuclear Weapons opened in Vienna on Tuesday.

NATO nations have not joined the treaty because they are under the US nuclear umbrella. Representatives from some member countries of the organization are taking part in the three-day event as observers.

The chief delegate from Norway noted that Russia's military attack on Ukraine "has fundamentally altered the European security landscape."

He said "Norway stands fully behind NATO's nuclear posture." He added, "We seek a constructive dialogue between all states to advance nuclear disarmament and counter polarisation in this area, even though we may have chosen different paths and tools to move towards zero."

The chief representative from the Netherlands compared the Treaty on the Prohibition of Nuclear Weapons with the Treaty on the Non-Proliferation of Nuclear Weapons.

The delegate expressed hopes that the former will supplement the latter to ultimately realize its goal.

The head of the German delegation said, "We fully share the goal of achieving a world free of nuclear weapons."

He noted Russia is threatening to use nuclear weapons, and China is expanding its nuclear arsenal in size and sophistication.

He said, "In such times, open-minded dialogue and an honest debate are all the more essential."