The BBC's Jon Manel, who was the first British broadcast journalist to report from inside the detention centre at Guantanamo Bay, assesses why President Obama failed in his promise to close the centre within 12 months.
To many, 12 months to close a prison probably seemed more than enough time.
In reality it was always going to be an ambitious target.
The Obama team was advised by one expert to set an 18-month deadline. I had personally been expecting it to take at least two years, so I was shocked that the new president thought it could happen so quickly.
Unfortunately for the Obama White House, it was not a simple case of "closing a prison". You cannot just transfer the inmates to a similar establishment down the road. "Gitmo", as the US military calls it, is a one-off.
The first problem was which prisoners to release.
Freeing to kill?
I know US officials and campaigners for Gitmo's closure who have wrestled with the concern that some of the detainees who are released could then go on to be involved in acts of violence which cost American lives.
Once decisions had been made about which prisoners were considered safe enough to be freed, the next problem was where to send them.
The Obama administration at least had global goodwill it could exploit, and several countries have re-housed prisoners. But that goodwill was always going to diminish if none of the prisoners were allowed to resettle in America.
That leads to the problem of US public opinion. A Gallup poll in November 2009 found almost two-thirds of those questioned were opposed to the detention centre closing and to prisoners being brought to America.
Many politicians on Capitol Hill - including Democrats - were not going to risk electoral defeat by being accused of allowing "terrorists onto American soil".
One of the issues which occupied officials in Washington for months was what to do with prisoners who could not be prosecuted due to insufficient admissible evidence, but who were considered to be too dangerous to be allowed to be freed.
Not only was there the question of the legal basis of how they would be detained but, once again, where would they be held? Surely they would have to be brought to America, but Congress prevented that from happening.
Then there were the 98 prisoners from Yemen. The administration was deeply worried about sending them home due to the security situation there. Yemen was a concern long before it hit the headlines in recent weeks.
If the Obama presidency was to have any chance of overcoming these obstacles, it had to hit the ground running. But it was some time before the real work started.
President Obama finally conceded in November that the deadline would be missed, but by then everyone knew it would be.
The question now is will "Gitmo" even close this year? In fact, it could possibly even be a question of whether it will close at all.
Closing Guantanamo was broadcast on BBC Radio 4 on Tuesday, 12 January 2010 at 2000 GMT, and repeated 17 January at 1700 GMT. You can listen via the BBC iPlayer or download the podcast.