Study some history and look at the numbers to see why "Buying American" and supporting domestic manufacturing is so important to our national security. We will lose on a global scale (in more ways than one) if we don't have a strong domestic industrial base.
Military production during World War II
There is an interesting video series from ABC in 2011 done by reporter David Muir. If you have time to watch these, it will be eye opening. Our small purchase decisions over time can have a big impact on our nation's economy. Here is Part 2 below.
Alliance for American Manufacturing has some great videos why American manufacturing is so important to our economy.