alt Hacker NewsChina has been involved in other conflicts, notably Vietnam and Korea. I don't put them in the category of imperialist ambitions however, for several reasons.
First, they're in China's backyard. China doesn't want a hostile imperial power on their border any more than Russia or the US does. Just look at the Monroe Doctrine, which now apparently includes kidnapping Venezuela's president.
Second, in those cases China was helping defend a nation from an invader, The Korean peninsula is a little more complicated. The Western version of this conflict is that the North Korea just upped and invaded one day for literally no reason. A more accurate history would have to include the military dictatorship the US installed on the peninsula when it was freed from Japanese occupation post-WW2.
As for the islands, which are in the South China Sea I might add, I'm more sympathetic to China's position here. That position is that the US is engaging in a deliberate strategy of maritime containment through a ring of islands and military bases, called the Island Chain Strategy [1]. It's not a secret. I personally think this is a pointless and unjustifiable strategy, built on a false premise (of containing Chinese imperialism).
The Phillipines are a US client state. So is Japan. So is Taiwan. So is it any wonder than China is grabbing these islands before the US or one of its clients occupies and militarizes them? I mean really... what business does the US have interfering with islands off the coast of China?