The RFE/RL live blog says Russian armored vehicles reported at Kerch. This is the logical route for heavy equipment. Airlift generally doesn't bring in the heavy stuff in any quantity.
Ukraine says they will fight:
"Ukraine is a peaceful country but it will protect its sovereignty and territorial integrity from an aggressive war with all possible means in full compliance with the UN charter," Ambassador Ihor Prokopchuk told a session [of the OSCE].
The question is can Ukraine's military fight? Is it loyal to Ukraine and can it get on the road and conduct an offensive into Crimea?
Or move into Transdniester, if Ukraine's only option is to grab a bargaining chip?
The question's answer is mixed. Most analysis assumes Russia is vastly superior. While Russia is stronger, I don't think it is that certain.
Russia has a much larger military, but Russia has a vast country to protect. And for ground forces, figure they really only have about 100,000 troops that are decent.
Ukraine's army is smaller, under 70,000. Plus paramilitary forces minus however many riot police were dismissed after the bloodshed in Kiev. But they have a smaller country.
It would have been better for Ukraine to be sitting on the defensive while forcing Russia to attack. Defense is easier for lower quality troops.
But with Russia starting out with Sevastopol, which was an airhead deep inside Ukraine to start, Russia has been able to go on strategic offense while putting themselves in position to be on operational defense. That's a good position to be in. Russia stands on the terrain Ukraine wants, and so despite being the victim must muster an offensive to push the Russians out.
And risk the Russians then moving into eastern Ukraine to pull the same thing there.
But what of the Ukrainian ability to fight?
Good question:
[Owing] to its legacy of Soviet bases to support any ground war to the west, the military is poorly positioned to counter an attack from the east, according to Ruslan Pukhov, the director of the Center for Analysis of Strategies and Technologies, a military research institution in Moscow. The thin military presence in the east complicates any response if Russia chooses, for instance, to back pro-Russian activists who have reportedly seized administrative buildings in Kharkiv, in eastern Ukraine.
According to its website, the Ukrainian military has a total of 130,000 people under arms, with reserves of some one million. While conscription recently ended, it remains a largely conscript army. Ukraine has partially reformed its military since the Soviet days, when it was organized in large-scale divisions. It is now organized on the more flexible brigade system and has been reducing the size of its military forces, but it is underfunded with a lot of outdated hardware. ...
In general, the Ukrainians are considered to have excellent home-produced tanks, but have also relied in part on the BMP-1, an infantry fighting vehicle that is a combined armored personnel carrier and light tank dating from the early 1970s. Ukrainian air defenses, all produced in Russia and a generation behind, are considered weak. ...
“Now the force is somewhat pathetic.”
I'd noted the poor positioning of the Ukrainian military.
Ukraine's troops probably are fairly pathetic. They did contribute to Iraq stability missions in the early years, I'll add. But they are not well trained.
But Russia doesn't have a lot of trained troops, either. Much of Russia's armed forces can also be described as pathetic.
Ukraine does have the advantage of lots of heavy armor. It may be old, but old armor facing Russian paratroopers and naval infantry can do some damage if the Ukrainians are prepared to take some losses and keep moving forward. Television news says Russians just have 6,000 troops there. That isn't a lot for the entire Crimea.
But given time, the Russians can move in armor via Kerch. And send in more troops.
Ukrainian aircraft moved to intercept Russian fighters, according to news on TV right now, so maybe the Russians won't want to risk airlift for the time being.
But if Kerch is open for business, Russia doesn't need to do that given their control of the lines of communication in Crimea.
I just don't know if the Ukrainian military is capable of moving fast enough to Crimea to begin a counter-attack in time to beat Russian heavy armor reinforcements.
But I do know that if Russia gets away with taking Crimea without a war, that is no way to deter future Russian moves. I think Ukraine needs to fight even if they lose the war. After all, Russia doesn't have the manpower or money to retaliate by launching a general invasion of Ukraine.
Russia needs to pay a price for this and only Ukraine can make sure Russia is overcharged for their acquisition of Crimea.