The UN Treaty on the Prohibition of Nuclear Weapons (TPNW) prohibits its signatories from producing, stockpiling, selling and using nuclear weapons. The International Campaign to Abolish Nuclear Weapons (ICAN), which was awarded the Nobel Peace Prize in 2017, has hailed it as a "milestone."

Leo Hoffmann-Axthelm, ICAN's representative in Brussels, told DW that from now on there would be "much more pressure on nuclear powers to finally make good on their old promises to disarm."

Efforts toward nuclear disarmament have stagnated in recent years. Just a handful of powers possess the world's estimated 13,400 nuclear warheads. Some 90% are owned by the US and Russia, with the rest shared among China, France, Britain, Pakistan, India, North Korea and presumably Israel — an undeclared nuclear power.

These states have invested a great deal into modernizing their nuclear arsenals to boost effectiveness. Indeed, they seem more interested in modernization than disarmament. However, many of the world's non-nuclear states are no longer willing to accept this situation. In July 2017, 122 states voted in favor of the prohibition treaty being adopted — 51 have since ratified it, which is why it can now enter into force.

Are nuclear weapons really a deterrent?

So far, mainly states in Africa, Latin America and Asia have ratified the treaty. In Europe, only Ireland, Austria, Malta and Liechtenstein have joined on. The world's main nuclear powers have so far refused to ratify it, as have NATO's 30 member states which consider atomic weapons essential for reasons of deterrence. NATO has insisted that as long as nuclear weapons exist, it will remain a nuclear alliance.

Currently, there are an estimated 20 US nuclear bombs stored at Büchel Air Base in southwest Germany under a NATO nuclear weapons sharing agreement. In case of emergency, German air force pilots would fly the planes that drop the bombs. The scenario is rehearsed in an annual NATO nuclear exercise named Steadfast Noon that involves personnel from several allied air forces.

As a result, the German government has also refused to ratify the disarmament treaty. In October 2020, government spokesman Steffen Seibert pointed out that many countries continued to view nuclear weapons as necessary instruments of military conflict. "As long as that is the case, Germany and Europe are at risk," he said, "It is our view that it is necessary to maintain a nuclear deterrent."

German population rejects nuclear arms

The wider German population is less convinced. According to polls, two-thirds would like the government to ratify the prohibition treaty. About 170 lawmakers from over 100 cities and four states — including Rhineland-Palatinate, where US nuclear weapons are stored — have demanded the government do so.

While the government claims it is fundamentally in favor of a world without nuclear weapons, it says the prohibition treaty is not the right means of achieving that goal. German Foreign Minister Heiko Maas has said that a nuclear disarmament treaty that does not involve the world's nuclear powers is not useful. He thinks that the 1970 Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is a more appropriate instrument. Germany is one of 191 state parties, which include five nuclear powers, that have joined the NPT. However, its goal is only to prevent the spread of atomic weapons, not disarmament.

Jonas Schneider, a nuclear arms expert at the Berlin-based Institute for International and Security Affairs (SWP), agrees with Maas. He doubts that the prohibition treaty will lead to progress, although it has received considerable praise.

"States that possess nuclear weapons profit massively from them, both in terms of defense policy and in other areas, with regard to other states," he said. Moreover, conventional weapons could not simply replace nuclear weapons, whose "deterrence effect is unique." He said that nuclear disarmament could only take place gradually and with the involvement of all nuclear powers.

As it comes into force, the Treaty on Prohibition of Nuclear Weapons remains controversial, with detractors doubting it will lead to much. But Setsuko Thurlow, an 89-year-old Japanese woman who survived the atomic bombing of Hiroshima, is more hopeful. She thinks that the treaty will mark the beginning of the end for nuclear weapons.