Interception of spy planes is perfectly normal as is flying them. After all there are literally thousands of photographs of Russian Birds with American fighters in tow. The issue is the attitude towards the spy plane. The description of the incidents both the EP3 and this latest show PLAAF pilots looking to swap paint. Highly aggressive behavior in the form of ramming, wing smacking and in this case a full stunt show over the bird. By contrast American interceptions are downright cordial "You Boys better go home now" being the biggest stunt pulled by a raptor pilot on a interception of Iranian fighters.as long as the spy bird is in international air space she is open to do as she pleases. That's a fact. A interception in international air space is no issue either but there are rules of conduct that are supposed to be followed between the interceptor and the intercepted, that's what's wrong.
Thing is, this particular interception was likely preceded by many other, far less confrontational ones.
If what the pentagon is claiming actually happened then it was without doubt a potentially dangerous act. But to only focus on the individual event rather than the strategic causes of it is tunnel vision and will only lead to more events like this in future.
If you continue backing someone into a corner they will eventually start to resist.