Nuclear-capable nations are growing their weapon systems, report finds

The world's nuclear powers have reduced their overall warhead counts since last year but are still invested in modernizing their weapons systems, according to a new report from an international research institute.

The Stockholm International Peace Research Institute (SIPRI) on Monday put out its annual report on the world's nuclear forces, which highlighted the status of the nine states in possession of nuclear fission- and fusion-based explosives. The United States and Russia maintain the world's biggest arsenals, with around 7,000 and 7,290 warheads, respectively, while Britain, France, China, India, Pakistan, Israel, and potentially North Korea together keep the rest of the world's approximately 1,100 remaining weapons.

The estimated 15,395 warheads comprising the world's total 2016 inventory is a step down from last year's 15,850 and 2014's 16,350 warhead totals, but the SIPRI report points out a slowing rate of disarmament that has occurred since the 1980s, when around 70,000 warheads were spread around the globe.

While SIPRI was able to obtain estimates of warhead totals for each country, Israel and North Korea's forces were more difficult to judge as both maintain "opaque" nuclear programs. The SIPRI report projects Israel to have around 80 stored warheads despite its reluctance to confirm or deny their existence, while North Korea could have around 10, although no evidence of the reclusive Asian nation's nuclear capacity has been released.

Of the nine countries known to possess nuclear weapon capabilities, only four – the US, Russia, Britain, and France – keep deployed, or potentially operational, warheads. The worldwide total of deployed warheads is around 4,120, of which the US and Russia have around 3,700.

Despite various nuclear reduction treaties enacted over the past years, including President Obama's 2010 New START nuclear reduction pact with Russia, the range of nuclear weapons already in place remains high. Russia and the US have yet to meet the reduced warhead levels mandated by the START agreement – 1,550 deployed warheads each – and there is skepticism that countries in possession of such weapons would ever wholly surrender their nuclear capabilities at this point.

"Zero is a concept that is desirable as a global initiative," former US Secretary of Defense William Cohen told The Christian Science Monitor in 2010, days before New START was signed, while adding that complete disarmament would be a difficult goal to reach.

"Is it feasible? I doubt it. Is it verifiable? I’m not sure," he said.

The authors of the new SIPRI study agree that the effects of proliferation may never be turned back, noting that despite the numeric decrease in warheads, all nine nuclear powers are "either developing or deploying new weapon systems or have announced their intention to do so." SIPRI estimated that the US alone plans to spend up to $1 trillion on "nuclear weapon modernization" over the next three decades, "in stark contrast to" Obama’s earlier pledges to commit to arms reduction, according to SIPRI associate senior fellow and study co-author Hans Kristensen.

"Despite the ongoing reduction in the number of weapons, the prospects for genuine progress towards nuclear disarmament remain gloomy," SIPRI Nuclear Weapons Project head and study co-author Shannon Kile said in an institute release. "All the nuclear weapon-possessing states continue to prioritize nuclear deterrence as the cornerstone of their national security strategies."