After joining the Chinese leader Xi Jinping for dinner last year, Mayor London Breed of San Francisco accompanied him to the airport to bid him farewell. There, on the tarmac, she made her request: pandas.

Her city’s zoo was faltering. Tourism was suffering and she faced a tough re-election campaign. A pair of pandas from China would be a political and public relations win.

What ensued were months of informal negotiations, with Ms. Breed — a politician with no foreign affairs or security experience — becoming a diplomat of sorts. She went to China, where she met the vice president and a deputy foreign minister, her calendars and emails show. She traveled with the editor of Sing Tao U.S., a pro-Beijing newspaper that registers as a foreign agent in the United States, according to other records and photographs from the trip.

All of this was organized by the Chinese People’s Association for Friendship with Foreign Countries, a group that American intelligence officials have concluded seeks to “malignly influence” local leaders. Unlike traveling Washington politicians, Ms. Breed received no C.I.A. briefing about what counterintelligence threats she might face in China and how officials there might try to manipulate her.

If Ms. Breed wanted pandas, China had an interest in the meeting, too — as a way to cultivate a relationship with the mayor of one of America’s most technologically important cities. There is no evidence of any quid pro quo or wrongdoing, but intelligence officials say that China is increasingly looking to wield influence in local governments as its sway in Washington diminishes.