THE world’s nine nuclear-armed states continue to modernise their nuclear weapons as the countries deepened their reliance on such deterrence in 2023, a Swedish think tank said today.

Wilfred Wan, director of the Stockholm International Peace Research Institute’s (Sipri) weapons of mass destruction programme, said: “We have not seen nuclear weapons playing such a prominent role in international relations since the cold war.” 

Earlier this month, Russia and its ally Belarus launched a second stage of drills intended to train their troops in tactical nuclear weapons, part of the Kremlin’s response to aggressive overtones from the members of the Nato military alliance.

In a separate report, the International Campaign to Abolish Nuclear Weapons (ICAN), which won the Nobel Peace Prize in 2017, said that the nine nuclear-armed states spent a combined total of $91.4 billion (£72bn) on their arsenals in 2023.

The group said that figures show a $10.7bn (£8.4bn) increase in global spending on nuclear weapons in 2023 compared to 2022, with the United States accounting for 80 per cent of that increase. 

The US share of total spending, $51.5bn (£40.5bn), is more than all the other nuclear-armed countries put together.

ICAN policy and research co-ordinator Alicia Sanders-Zakre said: “There has been a notable upward trend in the amount of money devoted to developing these most inhumane and destructive weapons over the past five years.”

She said: “All this money is not improving global security, in fact it’s threatening people wherever they live.”

Sipri estimated that some 2,100 of the deployed warheads were kept in a state of high operational alert on ballistic missiles and nearly all belong to the US or Russia.

Sipri’s director Dan Smith described the upward trend of warheads as “extremely concerning.”

The US and Russia together have almost 90 per cent of all nuclear weapons, Sipri said. 

In its Sipri Yearbook 2024, the institute said that transparency regarding nuclear forces has declined in both countries in the wake of Russia’s invasion of Ukraine in February 2022 and debates around nuclear-sharing arrangements have increased in importance.

Washington suspended its bilateral strategic stability dialogue with Russia, and last year Moscow announced that it was suspending its participation in the New Start nuclear treaty.

In Asia, India, Pakistan and North Korea are all pursuing the capability to deploy multiple warheads on ballistic missiles, the institute said. The US, Russia, France, Britain and China already have that capacity.