Swiss voters are casting ballots in a referendum to decide whether to enact new restrictions on guns and line up with Switzerland’s partners in the European visa-free travel zone who have already tightened gun rules following extremist attacks in Europe.

The proposal could require regular training on the use of firearms, special waivers for possession of some semi-automatic weapons and serial-numbering of major parts of some guns to help track them.

Supporters, including the Swiss parliament and executive branch, say similar measures adopted by the European Union after deadly extremist attacks in France are needed to ensure strong police cooperation and economic ties with Switzerland’s partners in Europe’s Schengen zone of visa-free travel.

Switzerland is in the Schengen zone but is not one of the EU’s 28 nations.

The issue, part of Switzerland’s regular referendums that give voters a direct say in policymaking, has stoked passions in a country with a proud tradition of gun ownership and sport shooting, and where veterans of obligatory military service for men can take home their service weapons after their tours of duty.

Opponents of the measure insist it will do little to stop terrorism. They say it will crack down mainly on lawful gun owners and ram through what they perceive as the latest diktat from Brussels on the rich Alpine country.

About two-thirds of respondents in recent polls on the issue say they supported the measure.

Switzerland has not faced major extremist attacks like those that have hit France, Belgium, Britain and Germany in recent years, leaving scores dead.