Do Americans feel that our National Defense is stronger than it needs to be? 

This graph clearly shows that Americans believed our national defense strength was the right amount from 1984- 2006 respectively. Only in 2006- 2008 do we see a resurgence of our national defense not being strong enough, and this was most likely due to the financial crisis of 2007 causing anxiety in many citizens due to them losing their jobs. Generally speaking though, Americans believe that our national defense is about the right amount.

The graph was retrieved here: http://www.gallup.com/poll/1666/military-national-defense.aspx