I personally feel incredibly sorry for all those who've lost their lives in the pointless exercise that was Iraq, but after realising that my government apparently feels as though it's entitled to sacrifice the lives of young men and women or reasons other han national defence, I'd beg anyone considering enlisting to re-consider their decision. Killing others, be they combatants or innocent people or fellow soldiers, risking your own life, and for no good reason, with relatively poor pay, is not a decent career path.
There are various jobs in the military; before you enlist, you take a test called the ASVAB, and the higher your score is, the more jobs you have to choose from.
Many of the jobs offered by the military are combat-related; others are not. They are merely technical or support persons.
Although they may be deployed to Iraq or Afghanistan, it is unlikely (although not impossible) that they'll ever be in a position where they have to kill anyone.
They're unlikely to see combat firsthand.
That is not to say they couldn't get blown up by a roadside bomb; anyone over there could.
But depending upon one's MOS (job), one might never even have to leave base.
I'm not saying your feelings are wrong; I felt
exactly the same before my son joined, and to some extent I still do: I'd encourage anyone who
has other reasonable options to explore those options.
On the other hand, i know a little more about the military now, and I know that joining- or even deploying- is not an automatic death sentence. Nor does it automatically mean you will go into combat and kill people.
Although everyone is trained to use weapons (in Basic Training), not everyone is likely to ever be in a position to need to use them.
After Basic Training is over, infantry soldiers get more advanced combat training, while soldiers in non-combat MOS's go to other bases to get specific training in their respective fields.