What action did the United States take in 2003 as part of its "War on Terror"?

In 2003, as part of its "War on Terror", the United States invaded Iraq.

The invasion of Iraq began on Thursday, March 20, 2003 when US forces began the first aerial bombardment of Iraqi targets with Tomahawk missiles launched from ships and submarines. While the American and British forces advanced from Kuwait, their Kurdish allies did so from the north. On Wednesday, April 9, the first US tanks entered Baghdad without encountering much resistance. On Thursday, May 1, 2003, President George W. Bush declared the end of the main battles.

President George W. Bush stressed that the invasion of Iraq was not an occupation but a "liberation". In the middle of that month, Bush said that the democratic Iraqi government would be established "as soon as possible". Before the invasion, Bush promised a rapid transfer of power to a democratic government, beginning with the drafting of an Iraqi constitution.

Deployed troops in the Middle East, which got the name of Iraq War. Note this was the second time they deployed troops in those regions, I say second due to Desert Storm and other operations that took place.