A Sweden-based, nonproliferation think tank says nuclear powers have continued to modernize their arsenals despite a decrease in the number of nuclear warheads.
The Stockholm International Peace Research Institute (SIPRI) said in a report released on June 15 that nine nuclear-weapon powers -- the United States, Russia, the United Kingdom, France, China, India, Pakistan, Israel, and North Korea -- together possessed an estimated 13,400 nuclear weapons at the start of 2020.
The number is down by 465 nuclear weapons in "a marked decrease" from the previous year, when the nine states possessed a combined estimated total of 13,865 nuclear weapons, according to SIPRI.
The decrease "was largely due to the dismantlement of retired nuclear weapons by Russia and the U.S. -- which together still possess over 90 percent of global nuclear weapons."
U.S. nuclear warheads dropped by 385 and Russia's declined by 125. Those large reductions were offset by slight increases in the nuclear forces of China, Britain, India, and North Korea.
The reductions in U.S. and Russian strategic nuclear forces were required by the 2010 Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms (New START) and completed in 2018. In 2019 the forces of both countries remained below the limits specified by the treaty.
Extending the New START treaty is the subject of arms negotiations that the top U.S. envoy for arms control said would begin with Russia later this month. The United States has also invited China to take part in the talks.
"The deadlock over New START and the collapse of the 1987 Soviet–U.S. Treaty on the Elimination of Intermediate-Range and Shorter-Range Missiles (INF Treaty) in 2019 suggest that the era of bilateral nuclear arms-control agreements between Russia and the USA might be coming to an end," said Shannon Kile, director of SIPRI’s Nuclear Disarmament, Arms Control, and Nonproliferation Program.
The INF Treaty was abandoned last year after the United States officially withdrew from it over accusations of Russian violations. Russia denied the accusations and in turn suspended its participation in the pact.
"The loss of key channels of communication between Russia and the USA that were intended to promote transparency and prevent misperceptions about their respective nuclear force postures and capabilities could potentially lead to a new nuclear arms race," Kile added.
New START, the last major arms-control treaty between the United States and Russia, is scheduled to expire in February 2021. The accord caps the number of nuclear warheads and so-called delivery systems held by the two countries.
While Moscow has pushed for a five-year extension, Washington has balked, saying it wants the deal to be broadened to include China.
China, whose nuclear arsenal is a fraction of the size of Moscow's and Washington's, has said it was not interested in participating in such talks.
Chinese Foreign Ministry spokeswoman Hua Chunying said on June 10 that Beijing hadn't changed its previous stance that it was not going to join the talks, which according to Bloomberg will take place on June 22 in Vienna.
SIPRI said in its report that China was in the middle of a significant modernization of its nuclear arsenal.
"It is developing a so-called nuclear triad for the first time, made up of new land- and sea-based missiles and nuclear-capable aircraft."
SIPRI also said that India and Pakistan were slowly increasing the size and diversity of their nuclear forces, while North Korea continues to prioritize its military nuclear program as a central element of its national security strategy.
It noted that North Korea provided no information about its nuclear weapon capabilities, while Israel has a long-standing policy of not commenting on its nuclear arsenal.