[yannis]

No they did not. They are just encouraging and creating an illegal market. The US also lacked proper laws against the importation of antiquities. For all we know it could have come into the states on a military plane and ISIS would have nothing to do with it. No museum worth its salt, with professional curators and staff would have accepted such a "loot" and as a matter of fact also reputable auctioneers. In any case it is important to study artifacts in the context where they were found, stratigraphy, nearby archaeological sites etc.