China bolsters East China Sea claim, warns of 'defensive measures'

SHANGHAI (Reuters) - China on Saturday bolstered its claim to islands that Japan says it owns, warning that it would take "defensive emergency measures" against aircraft that failed to identify themselves properly in airspace over them.

Ties between the Asian powers have been strained for months by the dispute over the East China Sea islands, called the Diaoyu in China and the Senkaku in Japan, which are believed to be surrounded by energy-rich waters.