Egypt has been preparing to evacuate its citizens from neighboring Libya after the Islamic State group released photographs Thursday of what are believed to be 21 Coptic Christians abducted by the extremists. Egyptian President Abdel-Fattah el-Sissi said his government would begin airlifting its nationals from the country, BBC News reported, citing the official Middle East News Agency.

The Egyptian government will “spare no effort in tracking down kidnapped Egyptian citizens” in Libya, el-Sissi’s office said in a statement late Thursday, according to Daily News Egypt. Egypt will also continue communicating with “official and unofficial Libyan parties” until “the situation is under control,” his office said.

The militant group formerly known as either ISIL or ISIS released the photos of what it claimed were kidnapped Egyptians in the latest edition of their online magazine Dabiq. The hostages were shown marching single file with their hands cuffed behind their backs and dressed in the orange jumpsuits typically worn by captives the group is planning to execute.

The Islamic State group claimed it kidnapped the Egyptian Christians to avenge Muslim women “tortured and murdered by the Coptic church of Egypt,” BBC News reported. Most active in Iraq and Syria, the terrorist group promoted its expansion into Libya as a way to “easily capture Coptic crusaders.”

Despite its instability, Libya continues to play host to thousands of Egyptian workers, who are primarily employed in the country’s construction sector. Egypt’s largest Christian minority group, the Copts have recently been targeted in Libya, with a number kidnapped in two raids in the northern city of Sirte in December and January. Egypt’s foreign ministry has made a point of warning citizens against traveling to the neighboring country, which has been besieged by militia violence and political turmoil since the Libyan Civil War that toppled the nation’s strongman Moammar Gadhafi in 2011.

Egypt recently cracked down on illegal migration into Libya, with intelligence officials and security forces launching an operation along their shared border to prevent any infiltration, according to a regional security director quoted by the Cairo Post. Security forces arrested 44 people in late January on suspicion of attempting to enter the country.