Switzerland played an active part in the TPNW negotiations, issuing a statement on the outcome in an explanation of vote. In 2018, the Federal Council set up an interdepartmental working group to review the treaty and its implications. It concluded on balance that the reasons against accession outweighed the potential opportunities, considering among other things that the disarmament aspects of the TPNW were unclear.
In 2018 and 2019, the Federal Council decided to refrain from signing the TPNW for the time being. At the same time, however, it decided that Switzerland would take part in future intergovernmental conferences as an observer and would re-examine its position on the TPNW.
At the end of 2018, Parliament passed motion 17.4241: 'Sign and ratify the Treaty on the Prohibition of Nuclear Weapons'. Based on this decision by Parliament, the Federal Council will review the question of accession with the assistance of external experts.