The U.S. State Department says Russia has placed tanks and artillery in position for possible use in Ukraine. They most likely would be supplied to separatist fighters who are seeking secession from Ukraine, but the possibility remains that Russia would use them to launch a full-scale invasion. Thousands of Russian troops are now stationed very near the border with Ukraine.
Ukraine's military boasts 160,000 frontline personnel, and another million reserves. They possess over 4,000 tanks, nearly 6,500 armored fighting vehicles, approximately 1,200 self-propelled guns, 1,000 towed artillery, and over 600 multiple-launch rocket systems. In terms of air power, Ukraine has roughly 400 total aircraft, including over 100 fighters, nearly 200 fixed-wing attack aircraft, 60 transport aircraft, over 100 trainer aircraft, over 100 helicopters, and nearly 40 attack helicopters.
Ukraine is not much of a naval power, with zero aircraft carriers and destroyers, and only a single submarine. Still, overall the Ukrainian military is ranked 21st in the world in terms of total strength.
Russia, on the other hand, has the world's 2nd strongest military. It has 766 thousand frontline personnel and nearly 2.5 million reserves. In terms of land systems, Russia's military has 15,500 tanks, almost 28 thousand armored fighting vehicles, nearly 6,000 self-propelled guns, over 4,500 towed artillery, and roughly 3,800 multiple-launch rocket systems.
As an air power, Russia has over three thousand total aircraft. This includes over 700 fighters, almost 1,300 fixed-wing attack aircraft, 730 transport aircraft, more than 300 trainer aircraft, almost a thousand helicopters, and over 100 attack helicopters. Russia also has an aircraft carrier, 63 submarines, and 13 destroyers.
In short, a war between Russia and Ukraine would not exactly be a fair fight. Which is no doubt exactly what Putin would want.