If Aliens landed on the White House lawn, what would we do?

How would we react to first contact with aliens? Well, it depends on how advanced the aliens are. If they are more advanced than us, I predict an increase in favor for a stronger United Nations or similar organization as nations scramble to determine how to best protect their interests. Regional organizations are formed based on protection of and furthering of common interests; no matter what our various historical squabbles, we are all human, and would unite against a non-human force. However, I personally believe that this strengthening of both the United Nations and of regional organizations would happen anyways.

If they are less advanced than us, I predict that we will attempt to interfere in their affairs. This may take the form of proselytizing religion, spreading specific political systems, The various powers of the world will all have different ideas of what to do, and these will manifest themselves in yet another conflict. This would result in a situation surprisingly reminiscent of the status quo – with the entire world agreeing that Something Good should happen, but having such staunchly different opinions on A.) what the Something Good is and B.) how to accomplish that Something Good.
Essentially, I believe that the introduction of aliens into our political landscape would change nothing.