Exemption from military obligation for Swiss nationals abroad and US-Swiss dual nationals
In peace time, Swiss nationals abroad are freed from recruitment and military service.
US-Swiss dual nationals resident in the USA cannot volunteer for military service in Switzerland. Swiss nationals in the US who are not US citizens at the same time can volunteer, if they are fluent in a Swiss national language.
As long as you are only temporarily in Switzerland (holidays / visit), no military obligation arises. However, should the stay last longer (i.e. studies / work), Swiss citizens will automatically be required to register with the relevant local authority.
In the event that the duration of your stay in Switzerland requires registration, you are no longer regarded as a Swiss national abroad and therefore you are subject to military obligation. Dual nationals who have already performed military services, civilian service or provided replacement services, are exempt from military service in Switzerland. However, they are subject to registration and may have to pay the military service exemption tax.
As a result of a treaty between Switzerland and the USA, US-Swiss dual nationals are exempt from military service and payment of the military service exemption tax for the first two years of their stay (for example, during their studies), as long as they were born in the USA, have always lived there and one parent is a Swiss national.
In short, as long as you live in the United States, you are not required to provide military service and you do not have to pay military service exemption taxes. However, as soon as you go to Switzerland for an extended period, an individual clarification is necessary.