Islamic State militants indulged in new public displays of artifact destruction this week, sledgehammering a half-dozen statues said to have been stolen from the ancient Syrian city of Palmyra.

The militants also broke up a hidden 2,000-year-old lion statue they discovered in a Palmyra museum garden and demolished a 13th-century tomb near the northern Iraqi city of Kirkuk.

The destruction, publicized in photographs and statements posted by the Islamic State on social media and corroborated by officials and antiquities experts, underscored the risks to the archaeological heritage sites in Syria and Iraq, as well as the impunity of the militants now in command of large parts of both countries.