US Secretary of State Antony Blinken warned China on Tuesday against using "coercion and aggression" as he sought to use his first trip abroad to shore up Asian alliances in the face of growing assertiveness by Beijing.

China's extensive territorial claims in the East and South China Seas have become a priority issue in an increasingly testy Sino-US relationship and are an important security concern for Japan.

"We will push back, if necessary, when China uses coercion and aggression to get its way," Blinken (above) said.

His visit to Tokyo with Defence Secretary Lloyd Austin is the first overseas...