What role should national security play in American government in regards to protection, aggressions, helping others, etc.?
I think that the previous response was well conceived. I would only add that one of the most vital roles that America can play in preserving its own national security and helping others would be with the sharing of information and intelligence. The threats that face nations are ones that are universal. Terrorism and the disruption of national security is something that all nations can and do experience. Being able to see this as a problem for all nations and not necessarily one that warrants unilateralism is of an essential nature. The ability to share information, communicate across national lines about what is known and what is perceived, and to be able to act in a joint accord to protect one another is something that all nations, not just America, can pursue. It is also something that will prove to be highly valuable as these nations collaborate on ensuring that terrorism and acts of terror are elements of the past that can be defeated. As the campaigns increase in success, the need to share information collaboratively and assist in this process will be of the utmost in importance. The recent attack on a Sufi Shrine, killing hundreds, is an example of how nations, communities, and cultures must all share information with one another to protect their own and everyone else's interests.
In my opinion, the United States should stick mainly with the ideas of the "realists" in international relations theory. The realists argue that countries should be concerned only about power and about having enough power to keep themselves safe.
In an ideal world, we would be able to help other countries become "better." However, we cannot always do that. We are having huge difficulties with this in Iraq and Afghanistan, for example. So I think that the main push of US foreign policy should be to keep our country safe by being strong enough to prevent other countries from attacking us. I do not think we are capable of making everyone like us or of making the world a perfect place, so I think we need to focus on security.