Isis is only continuing what the US and UK did during  Gulf War II when hell was let loose in Iraq and its ancient monuments were plucked, gutted, and burned.

Simon Jenkins at the Spectator.co.uk:

When I protested the dropping of high-explosive bombs near ancient Serbian churches during the Kosovo war of 1999, I was told it was unreasonable to expect the RAF to be pinpoint accurate in its targeting. The heirs of Bomber Harris are not squeamish about the far end of a bomb site, be it a human being or a historic building. There will always be ‘collateral damage’. On this 70th anniversary of the Dresden firestorm at least we say sorry. We did not do so at the time. We saw eliminating an enemy’s heritage and culture as justifiable revenge — as Harris’s apologists still do. That is roughly the Isis approach.

There is no point in the United Nations secretary-general, Ban Ki-Moon, declaring the destruction of Nimrud ‘a war crime’, or Unesco declaring it ‘a direct attack against the history of Islamic Arab cities’. There is in place a clear 1954 Hague convention protecting ‘cultural property in the event of armed conflict’. It remains unratified by two states, America and Britain, ‘for reasons of national security’. That is two states, plus the Taleban and Isis. As Robert Bevan has written in The Destruction of Memory (2006), the razing of history has long been the most hypocritical weapon of war.”