I think diplomatic means would work differently on China than Iran, the dynamics are different. The Iranian regime thinks “standing up to” the US strengthens its position. China knows its economy relies on the US and the rest of the Western world.
Also, tariffs on at least the illegally subsidized anti-competitive products would not be out of line.
China is now not in a position to dump US bonds. They simply hold too many. Sure, they could greatly hurt us by dumping bonds but they would greatly hurt themselves by doing so. They have made such significant investments in these bonds that they would lose billions of dollars if they started dumping the bonds as the value of the bonds they would still hold would greatly drop in value and they simply hold too much to dump them all at once before values would be affected.
As for where these bonds come from, the amount that came from ARRA (which the CBO estimates created 1.4 to 3.3 million jobs and kept the unemployment rate from climbing to a disastrous 12+ percent) pales in comparison to the amount that came from our Iraq adventure and tax cuts that did little to nothing to stimulate the economy or create jobs.