On December 6, 2014, two hostages held by al-Qaeda in Yemen, American photojournalist Luke Somers and South African teacher Pierre Korkie, were killed in a failed rescue attempt.

They were reportedly shot by their captors as a joint raid by US and Yemeni forces in the southern province of Shabwa unfolded, and are believed to have succumbed to their injuries while being transported to a US naval base.

This was the second such operation to rescue Somers - the US first tried to free him on November 25, which resulted in the rescue of eight other captives but not the 33-year-old American, who had been moved by his captors before that raid.

Hostages killed in failed rescue bid in Yemen

Korkie was set to be released on Sunday, according to a charity he was working with, but US President Barack Obama ordered the raid citing intelligence information which indicated that Somers' life "was in imminent danger".

But despite successful cases, these rescue missions always carry the probability of going awry, says Christopher Voss, a former lead international hostage negotiator for the FBI.

"As long as hostages are in the hands of terrorists who have the opportunity to murder them at any time, you can't take the promise that they can be released at its face value," Voss told Al Jazeera.

"It's very difficult to hold off a rescue mission because someone might be let go when you're fairly certain that someone is going to be killed."

Failed missions

Saturday's mission was not the first time the US military has tried, and failed, to safely bring home hostages with clandestine missions.

Failed rescue mission Operation Eagle Claw [AP]

1980 - Operation Eagle Claw, Iran

In April 1980, then-President Jimmy Carter ordered an operation to rescue 52 Americans held hostage in Iran by revolutionary forces after they took over the US embassy in Tehran in November 1979.

The mission was aborted after only five of the eight rescue helicopters arrived in the rendezvous area in Iran's central Yazd province in operational condition.

The remaining helicopters were either damaged or forced to return after encountering a sandstorm. 

One of the remaining helicopters had crashed into a transport aircraft resulting in the destruction of both vehicles and the death of eight US soldiers.

The hostages were released in January 1981 in a deal brokered by Algeria after intense rounds of negotiations between the US and Iran.

Six others US diplomats were rescued in a successful mission with the help of the Canadian government in events depicted in the 2012 film Argo.

 Scottish aid worker Linda Norgrove [AP]

2010 - Death of Linda Norgrove, Afghanistan

Scottish aid worker Linda Norgrove and three Afghan colleagues were kidnapped by Taliban fighters while travelling to Kunar, where she was to open a charity project in the eastern province on September 26, 2010.

Reacting to intelligence reports, David Cameron, British prime minister, approved on October 8, 2010, a US-led special operation to rescue Norgrove on the 13th night of her captivity.

US Special Forces conducted a pre-dawn raid at a hillside Taliban hideout where the 36-year-old Norgrove was being held, killing her and her captors in the process.

She was initially believed to have been killed by a suicide vest detonated by one of her kidnappers after being dragged into open ground during the raid.

However, a NATO investigation later revealed that she was in fact accidentally killed by an unauthorised grenade thrown by one of her rescuers.

Captured Somali pirates [File: EPA]

2011 - Four Americans held by Somali pirates

A guided missile destroyer was sent to rescue four US citizens held captive by Somali pirates, who were preying on shipping lanes through the Gulf of Aden and the Indian Ocean.

The four hostages aboard a private yacht SY Quest - Jean and Scott Adam and Phyliss Macay and Bob Riggle - were captured in February 2011 off the Omani coast.

US troops boarded the vessel and killed two hijackers, only to discover that the hostages were already dead. They were reportedly killed by their captors during the navy operation, 

Several of the hijackers surrendered and were taken into custody, and later stood trial.

US journalists James Foley and Steven Sotloff [Agencies]

2014 - Sotloff, Foley and other western hostages held by ISIL

The Pentagon acknowledged that it had conducted a secret mission earlier this year in an attempt to rescue hostages held in Syria by the Islamic State of Iraq and the Levant (ISIL) group, including journalists James Foley and Steven Sotloff.

However, the US troops failed to find the hostages at a makeshift jail where they were believed to have been held, and proceeded to carry out a wider search which was also unsuccessful.

The attempt was abandoned after the troops determined the hostages were no longer at the site.

A number of fighters belonging to ISIL were reportedly killed during the operation. Reports also suggested that the hostages were moved from the camp 24 hours before the raid.

ISIL later released separate videos showing the beheading of the journalists. Three other western hostages were also killed in a similar manner.

Follow Rahul Radhakrishnan on Twitter: @RahulRadhakris

Source: Al Jazeera