Satellite photos reveal disturbing images of Russian tanks massing along the border with Ukraine, and heavy lift cargo planes landing at a military base in Crimea.  Taken with the recent closing by the Russian navy of the Kerch Strait, blocking access to Ukrainian ports from the Black Sea and a renewal of fighting in Eastern Ukraine, analysts believe that a Russian invasion is a growing possibility.

News.com:

Reports of four heavy-lifting Il-76 aircraft, used for the rapid deployment of troops and heavy military equipment, flying into Dzhankoi near the Ukraine border from Anapa have added to those fears.  The 7th Guards Mountain Air Assault Division, an elite which also took part in the seizure of Crimea, is based at Novorossiysk – close to Anapa.

Dzhankoi air base was reinforced last week by a fourth mobile brigade of advanced S-400 'Triumph' surface-to-air missiles.  The missiles reportedly have a range of some 400km and can reach 30km high, giving Moscow the ability to deny access to the region by aircraft and cruise missiles.

Defence analysts have also scoured photos available on Google Earth to reveal a build-up of 100s of Russian main battle tanks at freshly built or expanded facilities right on the border with Ukraine. Masses of trucks, tanks and stores have been assembled at facilities including Kamensk-Shakhtinsky and Valuyki, Belgorod Oblast.

Ukrainian media reports large numbers of Russian armoured infantry vehicles have also been seen crossing Moscow's controversial Kerch Bridge into Crimea.

Russia has unilaterally declared the Kerch Strait its territory in blatant violation of international agreements that say the waters are "shared territorial waters."  What makes this so dangerous is that the Ukrainian navy is blocked from returning to its ports from the Black Sea and effectively blocked from leaving its ports.  Ukraine announced that it would try to navigate the straits, setting off fears of a naval confrontation.

But it is the military buildup along the border at the same time there is renewed fighting in the eastern Ukraine region of Donbass that worries analysts the most.

In particular, the enemy opened fire from 82mm mortars to attack the positions of the Joint Forces in Luhansk region: near the villages of Novotoshkivske and Khutir Vilny in the Popasna sector," the Joint Forces Operation's press service stated.

The crisis flared after Moscow moved suddenly to seal the narrow channel between the Black and Azov Seas.  Russian special forces seized three Ukrainian naval vessels attempting to pass through the Kerch Strait international waterway on November 25.

Under international law and a 2003 treaty signed by both Russia and Ukraine, the Sea of Azov is designated a 'free navigation zone' and the Kerch Strait is classified as 'shared territorial waters'.

Putin may simply be upping the pressure on Kiev with a display of overwhelming force.  But there are currently several U.S. warships in the Black Sea, and if there is any kind of a confrontation, they will become targets.

Or Putin may have determined that with the U.S. distracted by the legal troubles of its president, now is the time to settle the issue of Russian dominance in Eastern Ukraine.  If Putin has judged correctly, we will not risk a war with Russia over Ukraine, and scoring a quick victory would be an enormous propaganda triumph for Russia.

But what if Putin has figured incorrectly?  What if NATO responds?  Putin will invade only if he feels the response will be weak and ineffective.  At that, he may be right.