"One China" policy is a red line for Chinese

When Donald Trump took a telephone call from the president of Taiwan, he was sending a signal that could have massive implications for America's relations with China.

For forty years, Washington has recognised the so-called "One China" policy which says Taiwan is not an independent country but part of China, meaning the US only has formal relations with Beijing.

Victor Gao, a former diplomat and Chinese government advisor, told the Today programme that the phone call could cause diplomatic damage.