The Islamic State group have kidnapped at least 90 Assyrian Christians in northeast Syria, the Syrian Observatory for Human Rights said on Wednesday.The Britain-based monitor said the abductions took place on Tuesday after IS seized two Assyrian villages -- Tal Shamiram and Tal Hermuz -- from Kurdish forces in the province of Hassakeh.IS has destroyed churches and Christian shrines in Syria, and demanded that Christians living under its rule pay a tax known as jizya. Much of Hassakeh is divided between Kurdish and IS control.Fighters from the Kurdish People's Protection Units (YPG) have been on the offensive in the province in recent days. They have taken 24 villages and hamlets as part of an operation to try to recapture the town of Tal Hamis and surrounding areas.Tal Hamis lies to the east of the villages taken by IS on Tuesday. YPG forces have also been on the offensive in Raqa province, which neighbours Hassakeh, seizing 19 villages as they advance following their recapture of the strategic border town of Kobane last month. The Kurdish forces have been backed by US-led air strikes launched by the international coalition fighting IS. The Observatory said the coalition carried out a series of strikes around Tal Hamis on Tuesday that killed 14 IS members.On February 15, the Islamic State militant group released a video purporting to show the beheading of a group of Egyptian Christians who had been kidnapped in Libya. Egypt’s Coptic Church confirmed that the 21 workers were dead.In the video, militants in black marched the captives, dressed in orange jump suits, to a beach the group said was near Tripoli. They were forced down onto their knees, then beheaded.Following the incident, Egypt’s military carried out air strikes against the militant group's targets in Libya at dawn on February 16.“Your armed forces on Monday carried out focused air strikes in Libya against Daesh camps, places of gathering and training, and weapons depots,” the military said in a statement, using the Arabic acronym for IS.On February 3, IS released a video which purportedly shows the Jordanian pilot captured in December being burned alive.The video released online showed images of a man purported to be Maaz al Kassasbeh engulfed in flames while trapped inside a metal cage. Kassasbeh was captured on December 24 after his F-16 jet crashed during a a mission over northern Syria as part of the US-led coalition campaign against the militants.Jordan's warplanes launched strikes against the group, after vowing a harsh response to the burning Kassabeh alive. The announcement came as King Abdullah II personally paid his condolences to the airman’s family, which has urged the government to “destroy” the militants, reflecting deep anger among Jordanians over the brutal murder.