Why ISIS Take Hostage Assyrian in Hassakeh?

ISIS Takes Assyrian to Prisoner Swap with Kurdish Fighters, Newsweek reports.
The abductions of the 150 Christians took place yesterday after ISIS seized two Assyrian communities from Kurdish forces in the northeast province of Hassakeh.
Members of the ISIS stormed the Tell Tamer area in Syria on Monday morning, taking Assyrian villagers hostage.
The women and children were separated from the men, who were taken to the Abd al-Aziz Mountains.
After men and women were separated, one of the hostages contacted a relative in Canada who then got in touch with A Demand For Action (ADFA), an organization that fosters protection for Assyrians, Chaldeans and Syriacs.
The ADFA publicized the attack and hostage situation. Nuri Kino, the founder of ADFA, has been in touch with numerous relatives of those held hostage since the attack. Kino told Newsweek in a phone interview.
Kino and his organization attempted to reach villagers by phone, only to have a member of ISIS pick up. “[ISIS] told us that we should not call any longer since we cannot do anything about their situation,” ADFA said in a statement.
The terrorist organization demanded a prisoner exchange with Kurdish fighters; they are seeking the release of ISIS members in exchange for the villagers. The exact number of prisoners ISIS is looking to swap for is not known. They have threatened the lives of the village men, estimated to be more than 100, if the swap does not go through.
It is unclear how many ISIS fighters took part in the attack on the village or if any died in the ongoing clash. Kino said witnesses described the force as “massive” and the atmosphere as “a panic.”
“It’s panicking, but there are a couple of aid administrations who are trying to make their way there to help them as well,” he explained.
The Islamic State has a history of targeting Christians. Last week, ISIS fighters in Libya executed 21 Egyptian Coptics, an act denounced by Egyptian officials and religious leaders, as well as the Pope