The US-led invasion of Iraq in 2003 was second such war within a short space of time. The Gulf War of 1991 had seen UN forces (led by the US) invade Iraq after Saddam Hussein's armies invaded neighbouring Kuwait. The 1991 conflict was militarily one-sided, with a quick victory to the UN forces and the restoration of Kuwaiti independence. However Saddam Hussein remained in power.
The 2003 invasion of Iraq was part of the response to the 9/11 attacks of 2001. Afghanistan had been invaded by US-led forces within six weeks of the attacks. The Iraq situation was more complicated, with the US alleging:
- Links between Saddam Hussein and Osama Bin Laden's Al Qaeda organisation
- The existence of 'Weapons of Mass Destruction' in Iraq that would be used by Hussein against his people, his neighbours and Western governments, unless the West acted.
Hence the controversial launch of 'Operation Iraqi Freedom'.
Here's a news documentary from the time to help you get the picture:
At the time, there were widespread protests against the invasion. A common cry of the protestors was "No blood for oil", indicating that they thought the justifications for war were a cover for securing control of Iraqi oil.