– Secretary of Homeland Security Jeh Johnson urged a reluctant Congress on Thursday to allow the Obama administration to close the prison for terrorism suspects at Guantanamo Bay, Cuba, and to transfer the last 116 detainees to U.S. facilities.

President Obama has sought since he took office in 2009 to empty the controversial detention facility, which was set up after the 2001 terrorist attacks. But fierce resistance in Congress, where lawmakers say the facility safeguards Americans, shows no sign of abating.

More than 700 inmates have been held at Guantanamo Bay, at a cost of more than $5 billion, since it opened in 2002. Some of those released have rejoined terrorist groups overseas.

Speaking at a national security conference here, Johnson said it "doesn't make any fiscal sense" to pay nearly $900,000 per year to house each prisoner, for a total cost of more than $100 million a year. It costs the government about $80,000 a year to incarcerate an inmate in a federal prison.

The shrinking population at Guantanamo Bay, as inmates are transferred to other countries for custody or release, has not produced significant savings, Johnson said. The number of inmates has fallen from 242 in 2009 to 116 today.

Johnson also echoed Obama's frequent charge that the failure to bring any of the inmates to trial has undermined America's image overseas, especially because civilian courts have successfully prosecuted and convicted dozens of terrorism suspects.