I'm reading news on yahoo. One piece of news says:

...

U.S. President Bush's decision to send 21,500 additional troops to Iraq will put further pressure on the National Guard, whose 458,000 citizen-soldiers have a dual mandate to protect the nation both at home and abroad. The plan would 'remobilize' Guard troops to help support troop rotations.

...

I tried to look it up in my dictionary but faild to find the entry. So, is it a new term? And with due respect, what's citizen soldier? What's the difference between "citizen soldier" and "soldier"(or regular soldier)? Is a citizen soldier a civilian employed by the army temporarily so that after duty finished he/she can go home?

Thanks,

Callithump

Do inform me if you see any corrections needed in my written English.