World's nuclear arsenals on the rise as concerns grow over China and North Korea

People in Seoul watch a news broadcast showing footage of a North Korean missile test.

(CNN)The world's biggest powers might have once pledged to work toward a world without nuclear weapons, but global stockpiles are expected to rise over the coming decade, according to a new report.

"There are clear indications that the reductions that have characterized global nuclear arsenals since the end of the cold war have ended," the Stockholm International Peace Research Institute (SIPRI) said in a report Monday.
The report comes amid growing Western concerns over efforts by both China and North Korea to expand their nuclear capabilities. The US suspects North Korea is preparing to conduct its seventh nuclear test imminently, while China's Defense Minister Wei Fenghe told the Shangri-La Dialogue summit at the weekend that his country had made "impressive progress" in developing new nuclear weapons.
    However, while SIPRI reports that China is "in the middle of a substantial expansion of its nuclear weapon arsenal," it makes clear that China and North Korea are not the only culprits.
      "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 -- this is a very worrying trend," it said.
      On SIPRI estimates, the United States and Russia remain by far the world's largest nuclear powers, with 3,708 and 4,477 nukes respectively, while China has 350, France 290 and Britain 180. But China's warhead count has increased in recent years, up from 145 warheads in 2006 according to the institute. The Pentagon predicts the Chinese stockpile to "at least double in size" over the next decade.
      While the stockpiles of both the US and Russia declined in 2021, SIPRI believes an "alarming" longer-term trend will see both countries increase their stockpiles and develop more powerful weapons.
        North Korea's secrecy means it is hard to gauge its nuclear abilities. Some estimates put its current stockpile at around 20 nuclear warheads, though the US and other countries believe it is working to increase this number and its ability to deliver them.
        Pyongyang has conducted a record number of ballistic missile launches this year and on Saturday appointed top nuclear negotiator Choe Son Hui as its first female foreign minister.
        "North Korea continues to prioritize its military nuclear program as a central element of its national security strategy," SIPRI said, adding that "the country's inventory of fissile material is believed to have grown in 2021."
        The think tank, which included figures for the country in its annual report for the first time this year, said it believed North Korea now had enough fissile material to produce up to 55 warheads.
        But its ability to deliver these weapons remains unknown. In May, North Korea tested what appeared to be an intercontinental ballistic missile -- though the range of the weapon or its ability to deliver a nuclear warhead were unclear.
        "There is no publicly available evidence that North Korea has produced an operational nuclear warhead for delivery by an intercontinental range ballistic missile, but it might have a small number of warheads for medium-range ballistic missiles," SIPRI said.
        SIPRI also said India and Pakistan were making efforts to expand their nuclear arsenals. It said Israel -- which does not publicly acknowledge possessing nuclear weapons -- was trying modernize its arsenal. Stockpile estimates for India and Pakistan stood at 160 and 165, and for Israel, 90.
        Japan's Defence Minister Nobuo Kishi attends the Shangri-La Dialogue summit in Singapore on June 11, 2022.
        As recently as January, the world's five biggest nuclear powers -- also known as the P5, as permanent members of the United Nations Security Council -- pledged to work together toward "a world without nuclear weapons" in a rare statement of unity.
        However, Russia's subsequent invasion of Ukraine has raised concerns that nuclear weapons could be used outside a testing situation for the first time since the US bombed Hiroshima and Nagasaki in 1945.
        Since the start of the war Russia has repeatedly reminded the world of its nuclear strength in oblique references apparently aimed at dissuading Western countries from greater intervention. CIA director William Burns has also warned Russia may use tactical nuclear weapons in Ukraine.
        Now many nations -- even those without nuclear arms -- are rethinking their calculations. Japan, the US and South Korea have recently vowed to strengthen their shared nuclear deterrence strategy.
        At the Shangri-La Dialogue, Japanese Defence Minister Nobuo Kishi made unusually strong comments directed at North Korea and China.
        "The world has become even more uncertain," Kishi told Asia's premier defense summit. "Japan is surrounded by actors that possess, or are developing, nuclear weapons, and that openly ignore rules