Even the mayor of London, Boris Johnson, spoke out, citing events in Iraq and Syria as reason enough to justify the removal two centuries ago of the Elgin marbles, which are now at the British Museum, from the Parthenon in Greece.

Those who support repatriation say they find it dispiriting to be re-engaged in a debate that many felt was largely won. Tess Davis, a lawyer and expert on looted artifacts with the Antiquities Coalition, which favors repatriation, said Europe was engulfed in war last century, yet no one has argued, for example, that the Monuments Men should have kept the items they rescued during World War II because their safety in, say, France or Italy could not be assured.

“Iraq might be the hot spot today, but there is no reason to think New York will not be one tomorrow,” said Ms. Davis, who has helped repatriate stolen Cambodian artifacts held by the Metropolitan Museum of Art, Sotheby’s and others. “The 3,000-year-old statues now threatened in Iraq have seen a lot of empires come and go.”

Alexander A. Bauer, an anthropology professor at Queens College, said he disagreed that the best response to events in Syria and Iraq was “to increase the collection of artifacts by the West à la the 19th century.”

“This is a dangerous reaction, I think,” he said.

But Peter Tompa, a collector of ancient coins and a former vice chairman of the American Bar Association’s Art and Cultural Heritage Law Committee, said he agreed with a colleague who told him, “If the people of these lands are indifferent and even hostile to their ‘cultural heritage,’ what’s the point in reserving it for them to ignore or destroy?”

Pointing to China in the 1960s, he said in an email: “There was a time not too long ago when fanatics devoted to Mao’s Cultural Revolution purposefully destroyed an untold number of cultural treasures. Now the Chinese have regained their appreciation of their past, and luckily they can turn to America for access to artifacts that have been treasured here.”