Turkey’s efforts have spurred an international debate about who owns antiquities after centuries of shifting borders. Museums like the Met, the Getty, the Louvre and the Pergamon in Berlin say their mission to display global art treasures is under siege from Turkey’s tactics.

Museum directors say the repatriation drive seeks to alter accepted practices, like a widely embraced Unesco convention that lets museums acquire objects that were outside their countries of origin before 1970. Although Turkey ratified the convention in 1981, it is now citing a 1906 Ottoman-era law — one that banned the export of artifacts — to claim any object removed after that date as its own.

Thievery and looting are wrong, Turkey says, no matter when they occurred. “Artifacts, just like people, animals or plants, have souls and historical memories,” said Turkey’s culture minister, Ertugrul Gunay. “When they are repatriated to their countries, the balance of nature will be restored.”

Turkey is not alone in demanding the return of artifacts removed from its borders; Egypt and Greece have made similar demands of museums, and Italy persuaded the Met to return an ancient bowl known as the Euphronios krater in 2006.

But Turkey’s aggressive tactics, which come as the country has been asserting itself politically in the Middle East in the wake of the Arab Spring, have particularly alarmed museums. Officials here are refusing to lend treasures, delaying the licensing of archaeological excavations and publicly shaming museums.