According to a report, the number of operational nuclear warheads worldwide has increased in the past year. The nine official and unofficial nuclear powers had 9,576 operational warheads as of early 2023 -- a year-on-year increase of 136, according to the Nuclear Weapons Ban Monitor published by NGO Norsk Folkehjelp on Wednesday. The weapons would have a destructive power of "more than 135,000 Hiroshima bombs".

According to the report, the increase is mainly due to Russia and China, but India, North Korea and Pakistan have also expanded their stocks of nuclear warheads. "This increase is worrying and continues a trend that started in 2017," said Grethe Lauglo Östern, editor of the report.

However, the total stock of nuclear warheads, which also includes discarded weapons, continues to decline, according to the report. That number dropped from 12,705 to 12,512 in a year, due to the destruction of decommissioned warheads in Russia and the United States. Lauglo Östern warned that the total number of nuclear weapons could soon increase "for the first time since the Cold War" if the proliferation of new warheads is not halted.

The eight official nuclear powers are the US, Russia, Great Britain, France, China, India, Pakistan and North Korea. Israel unofficially has nuclear weapons. Russia has the most warheads with 5,889, followed by the United States with 5,244. Moscow and Washington together have 89 percent of the total nuclear arsenal, according to the report.

On Saturday, Russian President Vladimir Putin said he had agreed with Belarusian ruler Alexander Lukashenko to station tactical nuclear weapons on Belarusian territory. Belarus, which has been ruled by Putin ally Lukashenko since 1994, not only borders Ukraine, but also EU member states Poland and Lithuania.