russia-to-limit-u-s-military-observation-flights-ria-idUSKBN1EL0UT

In Syria and now Korea, Russia is pushing us out and taking over the #1 spot

This means they do not need them, they have other technology. Look at the tech when these flights started.

From what I see on TV shows, etc nowadays with satellites one can get an up-close view of what's going on the ground and there isn't so much need for photo ops from airplanes anymore.