“I believe Beijing accelerated plans to create an early test for the new administration because Trump publicly called into question the One China policy and because China judged it safer to provoke Obama than an unpredictable Trump,” Mr. Cronin said.

The statement by Mr. Cook, the Pentagon spokesman, made clear that the episode would not shake American determination to maintain a military presence in the South China Sea, where busy shipping lanes intersect with volatile rivalries over territorial claims. He said the United States would “continue to fly, sail and operate in the South China Sea wherever international law allows.”

The Obama administration says the United States does not take sides in the territorial disputes but wants to preserve freedom of navigation in the South China Sea, including for United States Navy ships.

China’s rapid buildup of naval and coast guard forces in the region, and its construction of military facilities on artificially created islands, has alarmed Southeast Asian nations that also claim islands in the sea. The Chinese government says the American presence there is provocative, and it has said so again since the drone was seized.

“China firmly opposes the frequent appearance of U.S. military aircraft and vessels in waters facing China for close-in reconnaissance and military surveys,” Hua Chunying, a spokeswoman for the Chinese Ministry of Foreign Affairs, told reporters in Beijing on Monday.

When reporters pressed Ms. Hua on China’s reasoning, she asked, “Are you implying that the South China Sea is in the pocket of the United States?”

But a brief online statement on Tuesday from the Chinese Ministry of National Defense did not mention tensions over the United States presence, merely confirming that it had “smoothly completed” the return of the drone after “friendly consultations.”