This is how you solve such problems.

Assume 这个说法对 and 美国人了解这点, then there is no need to let them know.

Assume 这个说法对 and 美国人不了解这点, then the bigger issue is why someone who doesn't know such simple fact got into a position that can 分派工作. Now you have identified a bigger problem. When you face multiple problems, you should always tackle the most serious one first.

The conclusion is obvious.