NAGASAKI - The world's nine nuclear powers have an estimated 12,720 warheads as of June 1, slightly down from a year earlier, but researchers here said the weapons have become more sophisticated and the risk of nuclear warfare is rising.
Nagasaki University's Research Center for Nuclear Weapons Abolition RECNA produced an at-a- glance poster showing how many warheads each country had based on government documents and other sources.
Russia and the United States together accounted for 90 percent of the 12,720 nuclear warheads around the world, which was down 410 from the previous year.
Russia had 5,975 warheads, a decrease of 2,539 from 2013 according to the latest figures.
Of the 2,539 warheads, only 39 were in military stockpiles for potential use, either deployed with operational forces or held in reserve. The others had been retired and were scheduled to be dismantled.
The United States owned 5,425 warheads, a decrease of 2,225 from 2013.
Most of the reduced warheads had been retired and scheduled to be dismantled, like Russia. Only 942 warheads were slashed in military stockpiles.
Russian President Vladimir Putin threatened to use nuclear weapons after Russia invaded Ukraine on February 24.
The United States plans to upgrade its missiles and other warhead delivery systems through 2080, but Moscow is ahead of Washington in hypersonic arms development.
Akira Tomizuka, an associate professor of environmental physics at Nagasaki University, said that the United States and Russia are failing to fulfill their disarmament obligations under the Nuclear Nonproliferation Treaty.
While the two countries have reduced the number of warheads, they have no intention of giving up their arsenals and have improved the quality of their weapons, he said.
China is building a silo believed to be used to launch intercontinental ballistic missiles ICBMs, according to intelligence reports.
North Korea, which has resumed testing-launching ballistic missiles, has expressed a willingness to use nuclear weapons for pre-emptive strikes, saying the role of such weapons is not limited to deterrence to war. There are signs that the reclusive state is gearing up to conduct a seventh nuclear test.
Since 2013 the poster of the RECNA has been updated. It has been distributed to libraries and other facilities nationwide.