Dhaka, Dec. 4 -- Taiwan expressed thanks and China was upset on Wednesday after President Donald Trump signed into law legislation requiring the US State Department to regularly review and update guidelines on how the United States officially interacts with Taipei.

The United States is Taiwan's most important international backer despite the lack of formal diplomatic ties, and the issue is a constant source of irritation in Sino-US relations given Beijing views the democratically governed island as its own.

In 2021 under the first Trump administration, then Secretary of State Mike Pompeo lifted restrictions on contacts between US officials and their Taiwanese counterparts, put in place after Washington recognised Beijing in 1979.

The T...