President Barack Obama announced on Oct. 21 that all U.S. troops would leave Iraq by the end of the year. This marks the finale of a war that raged for nearly a decade and cost America approximately 4,400 lives and more than $800 billion. The result: a somewhat stable and democratic nation in the middle of a volatile region. Whether or not the Iraq mission was a success or whether it was necessary at all will be debated for generations to come. But one tangible thing Americans can walk away with is a great lesson that shouldn’t be ignored.

Yes, the information used to support the Iraq War was faulty. The justification for going in changed depending on the angle of the question at the time. A tragedy that snapped America out of its bliss and made its people fearful on their own soil was exploited for political aims. Nevertheless, there is no going back in history, and what’s done is done. As Colin Powell once quipped, “you break it, you buy it,” and America paid more than it bargained for.

Now is the right time to close this chapter on American policy in the Middle East. There is no longer a good enough reason for U.S. troops to be stationed in Iraq. The surge that Republicans called for evidently did the trick. Violence is down from its peak in 2007, and the country continues to become more stable. America’s goals there seem less clear with every passing day, so it’s a relief to hear that the remaining 39,000 troops will finally be back home spending the holidays with their families.

The war might be winding to a close, but politics doesn’t rest. Many Republicans in Washington are calling the withdrawal irresponsible. They claim that once the troops are gone, Iran will move in, and terrorist cells will blossom once more, bringing violence back to Iraq. It’s time to face the facts.

One hundred thousand troops have already been withdrawn from Iraq, yet sectarian violence hasn’t risen. America will still have a presence—more than 1,700 diplomats, law enforcement officials and other professionals will remain until 2012. A 5,000-strong security contractor force will remain to protect those diplomats. And it isn’t as if our presence in Iraq stopped Iran from trying to subvert its neighbor before.

Unfortunately, America didn’t learn the lessons of the Vietnam War, but hopefully the second time’s the charm. War has changed, and not all missions require an enormous military occupation. Look at the Libya campaign as an example of exterminating a nasty dictator without all the hassle. Regardless of someone’s stance on going into Iraq, Americans need to be united on how we leave it.