More than 400 experts gathered on Monday for global talks on nuclear law, a timely development coming as Russia's invasion of Ukraine have triggered tensions around the prospect of a nuclear war.

Hosted by the International Atomic Energy Agency (IAEA) the UN's nuclear watchdog, the five-day conference in Vienna is a first for the organisation. Industry experts are expected to delve into pressing nuclear legal issues, including non-proliferation of nuclear weapons.

IAEA Director General Rafael Mariano Grossi said in a statement that the conference would help integrate the agency's work with that of its partner bodies at the UN as well as think tanks, NGOs and government agencies, in an effort that he said had been largely missing until now.

The talks are "an important opportunity for us to take stock and discuss nuclear law for the future," Grossi said.

Why is this important?

There are eight states in the world who declare to have nuclear weapons with five countries being signatories of the UN Treaty on the Non-Proliferation of Nuclear Weapons (NPT), among them, Russia and the US. Although not formally confirmed, Israel is almost universally considered the world's ninth nuclear power.

But despite Russia being party to the NPT — an international agreement seeking to eliminate the use of nuclear stockpiles — the country placed its nuclear forces on a heightened state of readiness soon after its invasion with Ukraine.

Last week, Moscow reported the test launch of the Sarmat intercontinental ballistic missile, a weapon it claims is capable of mounting nuclear strikes as early as this year.

UN Secretary-General Antonio Guterres said in March that the risk of a nuclear war "once unthinkable, is now back within the realm of possibility."

A multilateral ban on nuclear missiles — the Treaty on the Prohibition of Nuclear Weapons (TPNW) — only entered into force in January 2021, highlighting gaps in international laws specifically banning nuclear weapons. A total of 86 countries have signed the agreement — but not a single nuclear power — while 60 are state parties to it.

What else is being discussed?

Experts gathered in Vienna will also be tackling issues around safety of nuclear energy and whether the low-carbon electricity source could help address the climate crisis.

On the radar are Small Modular Reactors (SMRs) which some experts hope could be used to generate electricity en masse, in place of large conventional reactors considered more risky.

Meltdowns of large reactors caused the Chernobyl and Fukushima disasters in 1986 and 2011 respectively. Both sites are still radioactive.

IAEA boss Grossi is presently leading a team of scientists to the Chernobyl site to restore monitoring systems after the plant was briefly held by invading Russian troops.

Edited by: Mark Hallam