Why iraq's people kill soldiers

U.S. and U.K. release iraq's people from suppression.
But iraq's people kill soldiers of U.S. and U.K.
Why?
 
Please teach...

Saddam, though an evil dictator, managed to achieve one thing, he managed to bring relative peace among the various ethnicities of Iraq.
He did this through the barrel of a gun and through force of arms, not unlike the method used by the US and UK recently to introduce democracy.

Thousands of people died in the war, millions exist in a state of martial law with little rights and ruled by an unelected totalitarian regime backed by the US, what has improved?.
The people get sporadic a electricity supply, little petrol, have less food and more invasive policing than ever before but now they are being occupied by foreign powers that broke international law with an excuse that turned out to be a lie while continuing to back Israel in another illegal occupation and crusade all around the Muslim world.

To conclude ask yourself whether the people of Iraq are any less oppressed than they were before. The answer is no. Is the world a safer place with less terrorism? The answer is no.