Thanks!
Switzerland has been neutral since the end of the client status to France of the Swiss Confederation after the Napoleonic War.
Switzerland maintained a strong armed neutrality, with a rapid response force in their militia. Switzerland also maintained a strict neutrality towards all powers during ww2, firing for example at both German and British and American planes when these by mistake or as provocation or test of defences ventured into Swiss airspace. Compare this to Sweden, Spain and Portugal, which all, willingly or coerced, breached the formal neutrality in favour of the Germans early war and the allies later in the war.
Yes, Switzerland was neutral during ww2. While the French, Italians and Germans did have plans for invasions of Switzerland, mostly in case any of the other powers tried to use Swiss territory as a way to get around border defences of their own country.
The Swiss had built an elaborate redoubt of fortifications, covering all the essential passes in the mountains, had stockpiles of food and ammunition to last them a long time, prepared and protected artillery position to cover all possible routes of enemy reinforcements and supply and had almost 500 000 men to call in.
The bottom line, despite the joint German-Italian plan Operation Tannenbaum to invade Switzerland, to do so would cost the axis extreme amounts in casualties, and would take several months, for very little gain. Switzerland could not provide what Germany needed - rare materials, oil, copper, led, iron ore, nickel, rubber, tungsten or chrome. Neither would the German-speaking population of Switzerland be especially enthusiastic about serving in the Heer - support for a unification with Germany was minimal at best.
So, bottom line. Too high a cost to break the Swiss militia in their well-prepared fortifications in their mountainous country for little or no gain.