The US has said that the visit of its envoy to India to Arunachal Pradesh highlighted America's "support for Indian sovereignty", a remark that could rile China, which claims most of the northeastern state as its own.
The envoy's "Tawang visit highlights resolute US support for Indian sovereignty and commitment to local partnerships", Alice G Wells, Acting Assistant Secretary of State in the Bureau of South and Central Asia, said in a tweet on Wednesday.
US funding supports joint public health and social sciences work in Arunachal by the University of South Florida and the Rajiv Gandhi University, she said.
Wells also shared a tweet of Juster in which he posted some photographs of the event and wrote, "Such an honour to be Chief Guest at the Tawang Festival and inaugurate the seventh edition of this wonderful celebration. #USIndiaDosti."
The Tawang Festival is organised every year by Arunachal's tourism department.
Juster also appreciated the presence of sports minister Kiren Rijiju at the festival.
In 2016, China had admonished the US for sending its the then envoy to India Richard Verma to Arunachal Pradesh, warning that a third party's meddling would only complicate the dispute between Beijing and New Delhi.
Rebuffing China for the objection, India had said that there was "nothing unusual" about his trip to a state that was an integral part of the country.
China considers Arunachal Pradesh as part of southern Tibet and routinely objects to visits by the Dalai Lama, Indian leaders as well as foreign dignitaries.
India-China border dispute covered 3,488-km-long Line of Actual Control (LAC) and the two countries have so far held 21 rounds of talks to resolve the issue. China claims Arunachal Pradesh as part of its southern Tibet.