Adm. John Aquilino, nominated to lead the US Indo-Pacific Command, warned Tuesday that the threat of China's aggression toward Taiwan may be more imminent than expected, while stressing the importance of the US-Japan alliance in regional security.

"My opinion is this problem is much closer to us than most think and we have to take this on," the current commander of the US Pacific Fleet told the Senate Committee on Armed Services, without specifying exactly by when he thinks the Chinese military may have the capability to invade Taiwan.