Switzerland and Austria have signed a declaration of intent to join the European Sky Shield air defense system, according to a BBC report.

The initiative was launched by Germany after Russia invaded Ukraine and is designed to allow European countries to buy defense systems together and train together.

It is seen as a historic moment for neutral Switzerland, but some Swiss fear the move jeopardizes their country’s longstanding neutrality.

Nobody could have imagined the creation and integration of countries into a pan-European defense system a few years ago, but Russia’s invasion of Ukraine showed the necessity of the initiative.

The continent is unstable and for many European countries upgrading their air defenses has become inevitable. The Swiss government says working with its European neighbors on a common system makes both strategic and economic sense.

Austria is also a neutral country, and the government in Vienna argues that the pooling and sharing of military resources is able to maintain the status of neutrality.

This is not the first time that Switzerland has circumvented its traditionally strict neutrality. As part of NATO’s cooperation for peace, it has been involved in the peacekeeping mission in Kosovo for two decades. It also joined EU sanctions against Russia, angering Moscow.

Nineteen countries have now signed up to the Sky Shield initiative, including the UK, the Nordic and Baltic countries, Hungary, Romania and Bulgaria.

When signing an agreement to join the initiative, Switzerland and Austria stressed that their neutrality remains unchanged, but this hypothetical question has never really had to be answered. They probably hope such a situation never arises.