Nalan Olcer, director of the Sakip Sabanci Museum in Istanbul, said, “In the case of the Louvre, there were similar pressures, because the French excavations are important” to France. “I think this should be a lesson for everyone to behave differently in the future,” she said during an interview last week.

But Germany says the return of the sphinx is a one-of-a-kind deal. “Both sides agreed that the sphinx is a singular case that is not comparable to other cases,” the German government said.

Turkey disagrees. “This is a revolution,” Mr. Gunay said last week about the agreement with the Germans. “This is a great development for the restitution of all our antique artifacts from abroad,” adding, “We will fight in the same way for the restitution of the other artifacts.”

Mr. Gunay hinted at a shift in the balance of power between his country and Western nations eager to pursue science, history and culture in the cradles of civilization around the Mediterranean. “Turkey has new universities, we have new archaeological institutes, and we have committed and successful archaeologists,” Mr. Gunay said. “So if we do not see the cooperation we hope for, then we will not hesitate to turn these excavations over to our own universities.”

Over the past decade, the Culture Ministry said, Turkey has doubled the number of its own archaeological excavations to 110, compared with 40 foreign-led projects, and increased its expenditures for such digs nearly a hundred-fold to $20 million last year. Museum revenues have increased fifteenfold to more than $100 million a year, thanks to an increase in visitors and more efficient administration that have allowed the country to reinvest in the preservation of its cultural heritage.

There is no justification left for claims that irreplaceable artifacts might be vulnerable to theft or neglect if returned to Turkey, said Ms. Olcer, whose museum has been lent masterpieces from the world’s leading museums.

Western archaeologists in Turkey, who asked not to be indentified for fear of repercussions, conceded that the sphinx would be well preserved in the recently upgraded museum at Hattusa.