About 20,000 young Swiss, including 61 women, have started their basic training with the militia army and the air force. For the first time the military service can be done in one stretch.
The majority of recruits will be doing a 15-week basic course in one of the more than 40 military schools across the country. Later in their career, they will have to do regular refresher courses.
On a trial basis, the army is also offering the possibility to serve the full 300 days in one stretch. Six months of initial training are to be followed by four months of service as guards, in surveillance, instruction and traffic regulation.
The defence ministry said a team of 800 professional army instructors and 4,000 militia officers were involved in the basic training.
Switzerland's national defence is based on compulsory military service. It maintains no standing army, except for a small permanent contingent of commissioned and non-commissioned officers.
In principle, all Swiss men have to serve in the armed forces until they have reached the age of 42. Staff officers remain in service until 52. Each soldier keeps his equipment in his own home, and receives compulsory marksmanship training.
Those not serving have to pay a military tax. Under the Swiss constitution, it is also possible to do a civil alternative service.
Military service for Swiss women is on a voluntary basis. Aged between 18 and 28, they can serve in all functions, except for combat duties.
Switzerland belongs to no international defence organisation. In 1996 it signed up to Nato's Partnership for Peace Programme. But the government said there were no plans to join Nato and give up the long-standing neutrality.
swissinfo with agencies