Why are we trying to make Iraq and Afghanistan safe when America's inner-cities aren't even safe?

There are about 30,000 gangs in the U.S. and approximately 800,000 gang members in the U.S. In the United States, one violent crime is committed every 22.2 seconds, one murder committed every 30 minutes. There are tons of areas, particularly inner city areas that I would not dare travel to. I live in Japan, and the image over here is that America is a dangerous country, which it is. Oakland, which has a huge gang and murder problem, has a gang task force of 8 police officers. Camden N.J. recently cut half their police force because of budget problems. The list goes on and on. So why isn't the richest country in the world not making itself safe first before spending trillions of dollars and hundreds of thousands of troops to secure other countries?