Australia's ambassador to the United States, Kevin Rudd, cautioned in a speech that the global consequences of a war over Taiwan would be as great as the impact of World War II, making the world "a radically different place."

If Chinese President Xi Jinping, who turns 71 this month, wanted to achieve "final national unification" with Taiwan, he would likely act in the next decade before he reaches his 80s, Rudd said in a speech in Honolulu on Thursday.

"We would be foolish to ignore the increasing clarity of China's military signaling, including the pattern of its most recent military exercises," said Rudd, who was twice Australia's prime minister in the previous decade.