For Japan, U.S. President Joe Biden's comment he would be willing to use force to defend Taiwan signalled no formal change in policy. But behind the scenes in Tokyo, it was seen as a welcome warning at a time of growing alarm over China.
Biden's remark on Monday - during his first Asia visit since taking office - appeared to stretch the limits of the U.S. policy of "strategic ambiguity" toward self-ruled Taiwan, to China's anger.
