Russia is deploying a tank battalion to Crimea:
Russian army armoured battalion has arrived in Crimea equipped with the first main battle tanks (MBT) to be deployed by Russia on the contested peninsula since the start of the stand-off between Moscow and Kiev last month.
The unit, which included more than 30 T-72 tanks, was shown to the international media being unloaded at a railway cargo yard near the large Russian air and logistical base at Gvardeyskoe on 31 March.
The article notes that heavier forces will allow the naval infantry of the Sevastopol garrison to be pulled back and allow the airborne units sent in to be redeployed; and that the armor would make it tougher for Ukraine to counter-attack.
This article is from April 1st, and reality may have already allowed the Russians to pull out forces as I speculated earlier. And with fewer troops there and just 30 tanks, that isn't much of an offensive force.
Other news is that the Russians continue to build up troops at Belgograd, which is on a main road north of Kharkov:
Airbus Defence and Space imagery captured on 21 March 2014 shows Russian troop formations deployed to a training centre west of Belgorod. As current reporting continues to illuminate Russian military deployments in the region, satellite imagery represents a method of verifying both equipment deployments and deployment locations. Troops deployed to Belgorod reportedly originate from the 76th Air Assault Division in Pskov and the 106th Guards Airborne Division in Tula.
Satellite imagery of the bivouac area at the Belgorod training centre, captured on 21 March 2014, indicates a significant presence of military vehicles consistent with those found in an airborne division. Furthermore, a significant number of tents are present to house personnel.
One, there is no way that the Russians are incapable of hiding troops within Russia from satellite surveillance. They are better than that. Which makes me think they want their deployments to be noticed.
Two, why push airborne units forward to the border when they could have remained in their home bases to be airlifted in on the eve of an offensive or landed inside Ukraine? Are the Russians really going to use their airborne force as an overland light mechanized invasion force?
My guess, from my distant vantage point and admittedly incomplete information via open sources that I've found, is that Russia is attempting to cast a giant shadow and appear threatening rather than being a preparation for invasion.
But you never can tell what might push Putin to invade Ukraine anyway if his rhetoric paints himself into a corner of Ukraine.