I disagree that the US wants to contain China, or anyone. Like the smallest nations, the US wants to protect its interests - and US interests are best served by a rising China. Similarly, China's interests are best served by working together with the US.
Excluding the Chinese themselves...
Don't know much about the terrorists who briefly took over the navy base, or the details of how they managed it. As for them destroying the Pakistani surveillance aircraft - why wouldn't they? Why would they even need a reason? It was there.
As for what foreign power might be behind such...