MIAMI, USA - This month marks 20 years since I, as a newly minted marine brigadier general, watched from the bridge of an Air Force C-17 as we began our approach toward the Guantánamo Naval Station Airfield. He Said to the Miami Herald.

Our mission was to set up a detention facility for prisoners captured in Afghanistan; we were tasked with preparing to secure at least 100 prisoners within 96 hours. The mission’s duration was to be 60 days, at which time we would be relieved by an Army-led Joint Task Force. No one expected the detention facility to be around more than a year. Twenty years and four administrations later, it is time to finally shut down the facility.

Though Guantánamo has long been used by U.S. administrations to house Caribbean migrants until their situations could be sorted out, the decision to use it as a detention facility for Islamic terrorists was hurried and ignored longstanding U.S and international norms for handling prisoners. Still, 35 prisoners remain at Gitmo.

They have been largely forgotten by the American people, though not by the rest of the world, which sees their incarceration as a renunciation of the values for which we profess to stand. Twenty of these prisoners have been recommended for release. But remain locked away at a cost of $540 million a year. The cost we incur to our reputation and credibility is harder to quantify — but much more damaging. Future elected leaders, diplomats and service members will all have to deal with the legacy of Guantánamo.