Claiming to know the mind of God is a bit presumtuous, don't you think? "Thou shall not kill" doesn't leave room for exceptions, mortal.
My point is God doesn’t approve of murder exactly as you stated.
The Commandment is often mistranslated as "thou shalt not kill" when it really reads "thou shalt not murder."
There is a huge difference between the two. If it really was "thou shalt not kill," then forget about being allowed to use deadly force to protect your family from evil (or perhaps try to shoot down a muslim terrorist who is killing our troops on US soil). There are situations in which justifiable homicide is necessary to save oneself or the lives of others. Going further into the Bible, into the New Testament, Jesus personally tells his disciples that they too should be armed with weapons, as they risked their own lives to preach His Word to others.