Seven NATO countries participated.The Romanian navy stated that these exercises involved commercial traffic monitoring.
Not a difficult task having in mind Ticonderoga class missile cruiser USS Vela Gulf was at hand and able to monitor anything that flies over Black sea and Ukraine.
Interesting coincidence. July 17th is the day MH17 was shot down.
Even more interesting is that NATO naval exercise saw nothing. Must be that AN/SPY radar was under maintenance. And the existence of this exercise was rarely if ever mentioned in the last two months.
Radar is line of sight. The curvature of the earth is such that you can’t “see” aircraft that are more than ~250 miles away, even at 30,000 ft.
The same reason that you can’t stand 100 miles away from a 14,000 ft mountain and see it.