Ian Explains: 20 years since the Iraq War: Lessons learned, questions raised

The 2003 US-led invasion of Iraq, dubbed "Operation Iraqi Freedom," began 20 years ago. The Bush Administration told the world that Saddam Hussein was developing weapons of mass destruction and the war would last weeks, but none of that was true.

In fact, almost nothing in the Iraq War went as planned. The US wasn't prepared for a violent insurgency that lasted years, killing thousands of US troops and hundreds of thousands of civilians. And two decades from its start, the war still casts a long shadow––the rise of ISIS, a civil war, ongoing violence and political turmoil.

With 20 years of hindsight, can we say the world is better off after the invasion of Iraq? What about Iraq itself? And what lessons can we learn to avoid repeating the mistakes of the past?

These are the questions Ian Bremmer asks US Senator Tammy Duckworth, who served in Iraq, and NBC's chief foreign correspondent, Richard Engel on GZERO World with Ian Bremmer. Watch the episode on US public television or right here: Iraq War's legacy: Loss of lives, rise of ISIS, & political turmoil