(NewsNation) — Russia carried out its attack on a large Ukrainian base on Sunday using air-launched cruise missiles fired from Russian airspace by long-range bombers, a senior U.S. defense official said on Monday.

The distance between where Ukrainian officials believe this missile was launched from in Saratov, Russia and the training facility near the Poland border is 1,141 miles. The Russian Kh-555 cruise missile, a modified version of a nuclear cruise missile, can strike from nearly 2,200 miles away.

This proves that the flying distance is crossable and it shows the limits, or lack thereof, of a no-fly zone.

If NATO were to impose a no-fly zone in Ukraine, then Russian planes couldn’t launch attacks over the country. However, missile attacks like the one that struck the base wouldn’t fall under that restriction.

Ukrainian missile defense systems have held up mostly well against these long-range attacks. From Sunday’s attack, they managed to stop 22 of the 30 missiles launched at the training facility.