Switzerland detonates all but one tunnel leading into other nations and destroys all but one bridge, which connects to France. All land highways entering Switzerland are land mine-active, protected by snipers and armed infantry of the Swiss National Guard. 40 interior sections of highways are converted into airstrips.
Switzerland begins to accept Swiss citizens back into the country, and only allowing foreigners out. This is dealt with force, if necessary. If unable to move out of the country, Switzerland will detain and deport when they are able to move out.
All Swiss dual, triple, etc. citizens residing in Switzerland are too renounce one/two/etc. of its citizenships, preferably the non-Swiss one, per unanimous Federal Council Executive Order 367. No need to renounce citizenship of those who are neutral+non-blue/non-red nations. In this, only one-citizenship Swiss citizens are allowed in.
Healthy refugees will not be allowed in.
Switzerland asks to be left alone in this conflict, repeating its nature of armed neutrality. Switzerland will act as a peaceful negotiator due to it being the holding nation of the UNHQ.