(United Nations) The fear of mushroom clouds towering above the skyline of a major world city has waned in recent years. Russia and the United States have cut back their stockpiles of nuclear arms, and head-on military clashes between powerful nations are rare.

But we are not out of the woods just yet. New data from the Stockholm International Peace Research Institute (SIPRI), which monitors the arms sector globally, shows that we are heading back to a world that is threatened by ever-more doomsday weapons.

The US-Russia disarmament deal is winding down and chances of a re-boot are slim. Meanwhile, tensions between nuclear-armed India and Pakistan, and the activities of Iran and North Korea, have revived fears of ballistic city-killers.

“Despite an overall decrease in the number of nuclear warheads in 2018, all nuclear weapon-possessing states continue to modernize their nuclear arsenals,” warned Jan Eliasson, a senior SIPRI official, in a recent statement.

There was some good news in the watchdog’s latest report. The estimated number of nuclear weapons in global stockpiles fell to 13,865 at the beginning of 2019, compared to about 14,465 at the start of the previous year.

Most of the global reduction came about thanks to the US and Russia – which together account for 90 percent of all nuclear weapons – reducing their arsenals under the terms of a deal struck in 2010, known as New START.

That deal is set to expire in 2021. There have been no serious talks on a successor treaty, and Washington and Moscow are wrangling over policies on everything from Syria to Venezuela, Iran, and meddling in the 2016 US election.

“The prospects for a continuing negotiated reduction of Russian and US nuclear forces appears increasingly unlikely given the political and military differences between the two countries,” said SIPRI arms expert Shannon Kile.

As the US-Russia deal comes to an end, the world’s other nuclear powers – Britain, France, China, India, Pakistan, Israel and North Korea – are either modernizing or increasing the size of their nuclear arsenals.

From 2018 to 2019, China increased its stockpile of nuclear warheads from 280 to 290, Pakistan’s expanded from between 140-150 to between 150-160, and North Korea added about 10 warheads, so that it now has between 20-30, according to SIPRI estimates.

US President Donald Trump’s efforts to pressure Pyongyang into scrapping its nuclear arms showed early signs of progress, but ground to a halt after a failed summit with his counterpart Kim Jong Un in Vietnam in March.

Meanwhile, the US president’s bid to use sanctions to pressure Iran into renegotiating a controversial 2015 nuclear deal has also proven problematic and raised concerns in a region through which much of the world’s oil flows.

Iran has been accused of developing nuclear weapons and the missile systems to carry them, but Tehran says it is only interested in enriching uranium for medical reasons, and so that it can harness atomic electricity.

In March, simmering tensions between India and Pakistan came to a head when the two nuclear-armed rivals launched air strikes in each other’s territories for the first time, sparking fears of a nuclear confrontation.

Those two countries are “expanding their military fissile material production capabilities on a scale that may lead to significant increases in the size of their nuclear weapon inventories over the next decade,” warned Kile.

These all represent big setbacks when viewed against the nuclear landscape from a decade ago. Back in 2009, former US President Barack Obama made a landmark speech in Prague in which he set out a vision for a world without nuclear weapons.

In 2016, Obama became the first sitting US president to visit the Japanese city of Hiroshima, where some 140,000 people were killed when the US dropped an atomic bomb in 1945 in the world’s first nuclear strike.

Now, more than a decade after Obama’s speech in the Czech capital, growing stockpiles of nuclear weapons and tensions between the big powers suggest that a Hiroshima-style attack may not be confined to the history books.

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