The global nuclear arsenal is expected to grow in coming years for the first time since the Cold War while the risk of such weapons being used is the greatest in decades, a leading think tank said on Monday.
Russia's invasion of Ukraine and western support for Kyiv has heightened tension among the world's nine nuclear-armed states, the Stockholm International Peace Research Institute said in a set of research.
While the number of nuclear weapons fell slightly between January 2021 and January 2022, the institute said unless immediate action was taken by nuclear powers, the number of warheads could soon begin rising for the first time in decades.
"All of the nuclear-armed states are increasing or upgrading their arsenals and most are sharpening nuclear rhetoric and the role nuclear weapons play in their military strategies," Wilfred Wan, director of the institute's weapons of mass destruction programme, said in its 2022 yearbook.
"This is a very worrying trend."
Three days after Moscow's invasion of Ukraine, which the Kremlin calls a "special military operation", President Vladimir Putin put Russia's nuclear deterrent on high alert.
He has also warned of consequences that would be "such as you have never seen in your entire history" for countries that stood in Russia's way.
Russia has the world's biggest nuclear arsenal with a total of 5,977 warheads, about 550 more than the US.
The two countries have more than 90 per cent of the world's warheads, although the institute said China was expanding, with than 300 new missile silos.
The institute said the global number of nuclear warheads fell to 12,705 in January 2022 from 13,080 in January 2021.
An estimated 3,732 warheads were ready with missiles and aircraft, and about 2,000 — nearly all belonging to Russia or the US — were in a state of high readiness.
"Relations between the world's great powers have deteriorated further at a time when humanity and the planet face an array of profound and pressing common challenges that can only be addressed by international co-operation," institute chairman and former Swedish prime minister Stefan Lofven said.
