War and Responsibility

What does it mean to 'accept full responsibility' as Rumsfeld averred?
My own reading of this includes some form of payment or atonement. A Roman general would have fallen on his sword, a Japanese official would have resigned and possibly committed seppuku, in the American Empire apparently just speaking the words is enough.

Is this now an American Empire? Certainly seems so, but we haven't acknowleged our empire in which case we run all the risks of empire without gaining any of the benefits.

The theory of Iraq invasion that makes the most sense in the real world is that we thought we needed a counterbalance to Saudi Arabia's control over oil. With Iraq in hand, we would control the second largest oilfields and would therefore have some leverage if/when the Saudis turned against us.

If it is an empire, do we guarantee our satraps democracy? How does that jibe with the mechanics of empire?