No, it is not as simple as you stated. So let me say in a layman's way. Due to economic crisis US offered to sell it's Treasury in the international market and it was for any and I repeat, it was for any country in the world to purchase the Treasure. Theoretically it could have been any country or many countries come together to buy US Treasury, the Treasury would have been sold in the market regardless, US Treasury is the safest. China in the meantime, loaded with US dollars saw a great opportunity to park it's trillion US dollars cash and jumped on the opportunity and bought the Treasuries. Did China do that for the love of US? no, but for it's own interest. Did that help US financially, of course yes as US need the cash pumped in. I said very early in one of my posts, It was a win win situation for both. No one did no one a favor and at the same time both countries did help each other. China ended up with US Treasury and US ended up with cash it needed.
This was not the first time or the last time for China. China has always steadily accumulated U.S. Treasury securities over the last few decades. As of today, only US forex is the safest bet. China owns approx. $1.08 trillion, U.S. national debt, which is more than any other foreign country except Japan.