U.S. President Barack Obama recently renewed his pledge to close the Guantanamo Bay detention centre, saying it is "not necessary to keep America safe, it is expensive, it is inefficient."

The statement was similar to comments made by Obama in 2008 when he first campaigned for the U.S. presidency, and vowed that if elected he would shut down the controversial facility on Cuban soil which houses many detainees arrested since the 9-11 attacks in 2001.

In one of his first acts after taking office in 2009, Obama directed the military to close the prison within a year. That never happened, and now, years later, he's making another attempt at fulfilling his promise -- at a time when 100 of the remaining 166 inmates are currently on a hunger strike and are being force-fed food on a daily basis.

But is Obama's goal realistic? CTV spoke with Richard Miniter, a military expert, investigative journalist and columnist with Forbes.com, about whether we'll see the end of Gitmo any time soon.

Following are some key challenges in closing the Guantanamo Bay detention centre:

What do you do with the inmates?

It was the Bush administration that first set the wheels in motion to phase out the detention centre known as “Gitmo,” sending a number of the "easiest cases" back to their home countries, Miniter said.

But now, more than a decade later, most of the remaining 166 inmates are considered "hard cases" -- meaning even their home countries don't want them and they are not welcome on U.S. soil either.

According to a U.S. Department of Justice report in 2010, 126 of 240 detainees were approved for transfer. Of those, 44 were transferred to countries outside the U.S. Another 48 were determined "too dangerous to transfer but not feasible for prosecution" and 30 detainees from Yemen were designated for "conditional" detention because the situation in their home country was too dangerous.

"They are not approved for repatriation to Yemen at this time, but may be transferred to third countries, or repatriated to Yemen in the future if the current moratorium on transfers to Yemen is lifted and other security conditions are met," the report stated.

Like the Yemenis, there is simply nowhere to send many of the prisoners who still remain in Gitmo.

Security concerns in home countries

And even in the "handful" of cases where inmates' home countries are willing to have them repatriated, such as Egypt, there are often major security concerns that make the repatriation extremely difficult, if not impossible to carry out, Miniter said.

"Egypt after the Arab Spring has opened its prisons and released thousands of radicals, including the brother of the current head of al Qaeda, Dr. Ayman al-Zawahiri. His brother, Mohammed al-Zawahiri, was released by the new Egyptian government. So anyone sent to Egypt might well be released and become a danger to America, Canada or our allies, so it's a real problem," Miniter said.

Torture/execution

The U.S. has a policy against returning prisoners to regimes where they could face execution, torture or other forms of abuse -- a policy known as “non-refoulement.”

In the case of a number of Muslim Uighers from China, they were provided with homes in Albania, Bermuda, Palau and Switzerland as a result of the policy, but it took years of diplomatic work to make that happen. And other Guantanamo prisoners over the years have had to fight plans to repatriate them to their home countries, claiming they would face certain torture if they were returned home, including a Libyan and a Tunisian.

"It's very difficult to place these people," Miniter said.

Lengthy litigation

Prisoners in Guantanamo Bay are subject to U.S. military proceedings. And the process is slow, Miniter said.

"Look at the case of Khalid Sheikh Mohammed, this is the mastermind of the 9-11 attacks," Miniter said. "He confessed, says he wants to be executed, but the U.S. is still in pre-trial motions in Guantanamo more than three years after he was first charged."

In the case of Omar Khadr, a Canadian who spent most of his formative years in the prison after being captured in Afghanistan in 2002, it took years of litigation, military court appearances and diplomatic wrangling before Canada was finally convinced to allow Khadr back onto Canadian soil as part of a plea deal.

Khadr was repatriated to Canada in September 2012 where he is serving the remainder of his sentence and is expected to be released in mid-2013.

But that is the exception. With 166 prisoners remaining in Guantanamo, each one potentially requiring years of court proceedings and diplomacy in order to move elsewhere, efforts to close the prison are likely to continue for years, Miniter said.

"Guantanamo is going to be around no matter what president is in the White House because there's nowhere to send these people," he said.