system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why did the US go into Iraq, and why are we still there?
gpt
Our stated reasons were to depose Saddam, who was suspected of constructing WMDs and supporting terrorism. In reality, his WMD programs had been defunct for years and he'd been blustering out of a desire to intimidate Iran, who was a much more pressing threat. Saddam's contact with terror organizations like Al Qaeda was also rather limited. To this day, a plurality of Americans think he was involved with 9/11, when no link has been found.

There were more personal reasons for many of the war planners. Bush had a grudge with Saddam after a failed assassination plot against his father following the gulf war. Some of the Bush cabinet like Wolfowitz, Rove, etc were involved in the Project for the New American Century, which even before 9/11 advocated invading Iraq for purposes of demonstrating and maintaining US power in a post-cold war world. There have also been allegations of corruption, less in the "we want their oil" sense, and more in that much of the reconstruction and contracting work went to firms such as Halliburton with ties to administration members, or to right wing think tanks who wanted to try out their ideas on the country's new government.

Why things went badly is a megapost in itself. The short version is that there was a power vacuum in the absence of the government, exacerbated by the decision to disband the Iraqi army. The government put in place by US-allied Iraqi exiles tended to be rather corrupt, and the country has fundamental problems with stability due to being comprised of three different populations (Kurds, Shiite, Sunni) who don't get along particularly well. Add to that no WMDs or solid terror links were ever found.

Anyway, we were stuck there for years trying to keep the country together. We were subjected to a pretty bad guerilla insurgency, and when the Iraqi government declined to renew the lease on US troops 10 years later, we declined to press the issue.

After that, regional instability in Iraq's northwest and next door in Syria, the arab spring uprisings, and sectarian militias that sprang up post-invasion all combined to create ISIS. They're really bad. We want them to go away. We're hesitant to do another full invasion, but we're kind of poking at them as best we can through airstrikes, drones, etc.