The opinion of Shaykh Abdullah Azzam – RA – on the issue of taking slaves/concubines which is similar to the situation we have today:
“And then if you’d ask for a fatwa from the zealous Arab youth that arrived to Peshawar and studied some fiqh, or so-and-so studied hadith;
‘Is it allowed to take Russian women, those that are in the battlefield and fight against the Muslims and then we captured them.. is it allowed to take them as concubines?!’
Of course the answer would be; ‘Yes according to the Shaykh so-and-so.’
And I say to him: It is not allowed for you, and also it’s is haram for you [to do so].. Why?!
Because if we were to take the Russian women, then they would take a hundred of Muslim women and violate their chastity… so should we then give a fatwa permitting this or forbidding it?!
If the taking of a single one as a concubine would lead to the violation of honor of a hundred of Muslim women, should we then give a fatwa of it’s permissibility or forbiddance?!
Thus, it’s a must for the one who gives a fatwa on a issue that he knows the details of the matter, and the place and situation that you are in, what is it really that you’re giving fatwa about?!
It’s imperative that you understand the subject completely based on the reality on the ground, not by looking into the matter as a personal theory in [issues of] Jihad.”
Fi al-Jihad Fiqh wa Ijtihad, p 58