The US has clearly violated international law, because the P-8 was spying within China's Air Defense Identification Zone. Of course, the US will say that it does not "recognize" China's ADIZ, but then the US also has an ADIZ that it vigorously enforces.
The real game, however, is that this is a part of the US strategy to "contain" China. It should also be noted that the US Air Force has been engaged in such types of "incidents" against Russia thousands of times (Russia must have done the same against the US). But the mouthpiece of Washington chooses to make a hypocritical public statement.
TANZHONGMING, from China Daily website