Kidnapping infidels and releasing them for ransom or enslaving them, as well as killing them if that option is deemed most advantageous for the Muslims, is fully sanctioned in Islamic law:

“As for the captives, the amir [ruler] has the choice of taking the most beneficial action of four possibilities: the first to put them to death by cutting their necks; the second, to enslave them and apply the laws of slavery regarding their sale and manumission; the third, to ransom them in exchange for goods or prisoners; and fourth, to show favor to them and pardon them. Allah, may he be exalted, says, ‘When you encounter those [infidels] who deny [the Truth=Islam] then strike [their] necks’ (Qur’an sura 47, verse 4)” — Abu’l-Hasan al-Mawardi, al-Ahkam as-Sultaniyyah (The Laws of Islamic Governance), trans. by Dr. Asadullah Yate, (London), Ta-Ha Publishers Ltd., 1996, p. 192.

“BREAKING NEWS: Three Americans ‘kidnapped’ by militia in Baghdad,” by Wills Robinson, Dailymail.com, January 17, 2016 (thanks to Robert):

Three American contractors have reportedly been kidnapped by militants in Baghdad.

According to Arab news channel Al-Arabiya, sources in the Iraqi capital city said the trio were abducted in the southern neighborhood of Dora on Sunday.

They were believed to have been with an interpreter, who has also been captured, reports suggest.

The US State Department has confirmed it’s aware of the reports.

Officials are working with Iraqi authorities to locate and recover the missing Americans.

Their identities and the reason they are in Iraq is not known.

John Kirby, State Department told Daily Mail Online: ‘We are aware of reports that American citizens are missing in Iraq.

‘The safety and security of American citizens overseas is our highest priority.‎ We are working with the full cooperation of the Iraqi authorities to locate and recover the individuals.’…

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