Taiwan's Vice President Lai Ching-te has made a stopover in San Francisco on his way back from Paraguay.

Lai departed Taiwan last Saturday. He also made a brief stop in New York on his way to Paraguay, where he attended the inauguration ceremony of the South American country's new President Santiago Pena on Tuesday.

As the US and Taiwan do not have official diplomatic relations, the chair of an organization handling unofficial relations, Laura Rosenberger, greeted Lai at San Francisco's airport on Wednesday. Rosenberger is a former senior White House official.

A reception was held at a hotel attended by people from Taiwan and others. Former US Secretary of Homeland Security Janet Napolitano also attended along with Rosenberger.

Lai said Taiwan-US ties were "unprecedentedly good" under the leadership of Taiwan President Tsai Ing-wen.

He went on to say that he will do all he can "to lead Taiwan continuously forward with peace as the lighthouse and democracy as the compass." Lai is expected to run in the upcoming presidential election in January as the ruling Democratic Progressive Party candidate.

Lai spoke briefly with US Interior Secretary Deb Haaland at the inauguration ceremony in Paraguay but it is not known whether he was in contact with US government officials while in the US.

Lai is returning to Taiwan on Friday. Beijing has said that China firmly opposes any form of official contact between the US and Taiwan. Observers are focusing on whether China will take countermeasures against Taiwan.