What does the red mean?

[v0031]

The Pentagon says it was a mistake, and "bad weather" may have been to blame. The Chinese aren't really buying it.


https://www.yahoo.com/autos/b-52-bomber-flies-within-191442792.html

[This account no longer in use.]

The Chinese government doesn't actually believe that explanation.

[muon2]

Confirming what CXSmith wrote, the phrase "to buy it" when applied to an explanation means to believe or agree with the explanation. The usage shows up with other types of concepts, often with "into". Consider this example:

The manager laid out an exciting new strategy to attract new customers to the store. The employees bought into it on the spot.

Here "bought into it" doesn't mean that the employees invested money. Instead it means they agreed with the strategy.