Mr. Wang said the adoption of the framework created a solid foundation for negotiations that could start this year, if “the situation in the South China Sea is generally stable and on the premise that there is no major interference from outside parties,” Reuters reported.

Few believe the framework will lead China to conclude a binding agreement anytime soon.

Perhaps even more important, in his first days in office, President Trump renounced TPP. That action, along with his years of denunciations of the trading policies of Japan and China and a promised “America First” pivot, seemed to many in the region to represent a significant retreat by the United States from its military and economic engagement here, and an important victory for China.

President Barack Obama had lavished attention on the region, where he spent part of his childhood and which has a population of more than 620 million and a collective economy of around $2.4 trillion, the third-largest in Asia behind those of China and Japan.

Geographically astride the world’s busiest and most strategic shipping lanes, the region was the fulcrum of the administration’s rebalancing toward Asia.

Mr. Trump has yet to demonstrate a similar interest or commitment to the region.

In his opening remarks to the conference, Mr. Tillerson sought to put to rest fears that the United States would abandon the region, saying that his multiple meetings with ambassadors were “indicative of the importance that the United States pays and places on this relationship with Asean.”

And while Mr. Tillerson chose not to meet with journalists on Sunday, his top diplomat for the region, Susan A. Thornton, the acting assistant secretary for East Asian and Pacific affairs, said that multiple visits by top administration officials had demonstrated its continued importance to the United States.

“The engagement is not a question,” she said.

Still, Ms. Thornton gave credit to the Chinese for supporting Saturday’s vote in the United Nations against North Korea.