Both Russia and NATO can't be right, so we decided to investigate further.
The map above shows every Russian military base The Washington Post was able to independently verify, with those singled out by NATO's satellite images highlighted. As you can see, there are a lot of military areas around, and those shown in NATO's images are only a small minority.
To put this map in context, the Post examined other available satellite imagery via Google Earth for the bases pictured by NATO in order to draw some preliminary conclusions. Of course, there's a caveat here: Both NATO and the Russians know more about this than we do and are likely not releasing all the information they have for obvious reasons.
What we have below should help you put Russia's military buildup, or lack of thereof, in context.
This military area does appear to have been expanded since 2011 to include a small airstrip. NATO's newly released images show about two dozen helicopters on the airstrip and in the surrounding fields. A large number of military vehicles and equipment are further to the south. Were the Russian army to advance on the Ukrainian city of Kharkiv, the path with the least physical obstacles would be from Belgorod.
2. Buturlinovka Air Base
Although reported as an abandoned airfield by NATO, military activity can be seen in pre-crisis imagery of this base from May 7, 2011, where it appears some 17 fighters are stationed. The most recent imagery from April 2, 2014, shows several dozen aircraft on the tarmac.
Surrounded by miles of small impact craters and entrenchments, the area appears to have long been used by the military for training. It is unclear from Digital Globe's March 27 image how many units typically train here and how often.
4. Near Kuzminka
From the NATO image, it appears that a large number of military units are training in this area. Far from urban centers and military bases, this area does not appear to have previously been used by the Russian military. The distance from this location to Donetsk is just 80 miles and there are few natural obstacles to slow the Russians if they wanted to enter Ukraine from this direction.
Located at the end of an air strip on the coast of the Sea of Azov, this base has seen military buildups as far back as 2006, as shown in the image below. The new imagery of March 22 does show a significant number of personnel stationed here. If these are airborne or special forces troops, they could quickly be moved to the nearby airfield and ferried by plane or helicopter deep into Ukraine.
6. Primorko-Akhtarsk Air Base
Imagery from August of last year shows an abundance of Russian aircraft already using this base. Digital Globe's limited-scope image from March 22 shows the addition of what appear to be transport helicopters. Whether the addition of these assets is typical activity for this air base is hard to tell.
What conclusions can we draw from this? In many of the locations highlighted by NATO, Russia appears to have had troops and military equipment almost regularly.
NATO's argument that these satellite images represent a military buildup does carry some weight though, especially near Kuzminka, where an isolated area not used for military exercises in the past is now seeing a lot of activity. Given Kuzminka's strategic location, not far from Donetsk, that certainly seems like something to watch.