On the issue of military alliances, China has one with Russia, and North Korea has been reported as being in a three-way alliance with Iran and Syria, so that if one is targeted by the US then the others will target US interests in their own neighbourhood opening up a second front. If East Asia goes up so does the Middle East or vice-versa.
Yes, I remember hearing about the undetected Chinese submarine revealing how modern and high-tech the Chinese military is becoming.
As for Chinese-US conflict erupting at some stage in the future,I think it is inevitable. The US will never willingly give up their place in the world whilst China won't back down from a confrontation and won't be told what to do by anyone. The world doesn't seem big enough to accommodate the two of them yet alone East Asia.
As soon as China has aircraft carriers it'll be game on.
