Putin has ordered a Russian military exercise right next to Ukraine.

President Vladimir V. Putin ordered a surprise military exercise of ground forces on Ukraine’s doorstep Wednesday, intending to demonstrate his country’s military preparedness amid tensions with Europe and the United States over the turmoil gripping Russia’s western neighbor.

Mr. Putin’s order applied to forces in western Russia and air forces across the country, and a separate order issued by Defense Minister Sergei K. Shoigu included unspecified measures to ensure the security of Russia’s Black Sea Fleet in southern Ukraine’s Crimea peninsula, a region that was a part of Russia until 1954 and is still heavily populated by ethnic Russians.

The Russian muscle flexing came as thousands of ethnic Russians demonstrated in Crimea’s regional capital of Simferopol, protesting the political upheavals in Kiev that felled the pro-Moscow government of President Viktor F. Yanukovych over the weekend and turned him into a fugitive.

“Crimea is Russian!” some screamed, as brawls erupted with rival demonstrators from Crimea’s ethnic Tatar population who support Kiev’s new interim authorities created by the Parliament.

Ukraine is primed for civil war. Russia is primed for building up its alternative to the European Union, the anti-democratic and Moscow-dominated Eurasian Union. Ukrainians tend to tilt west toward the EU; Ukraine’s ethnic Russians (about 17% of the population of Ukraine) tilt east toward Moscow. Ukraine needs a lot of money in aid and loans to bail its economy out. The EU is militarily weak and with the Obama administration now slashing U.S. defense forces to a level not seen since the end of World War II (as many of us warned in 2008 that he wanted to do), Defense Secretary Chuck Hagel declaring the “end of American military dominance” as the administration ramps up domestic entitlement spending, the West won’t be in much of a position to do anything if events lead to confrontation. Weakness (and the perception of weakness) begets confrontation. Obama’s force cuts could end up encouraging Putin to act.

Putin is a nationalist autocrat, and he isn’t stupid. If anything, he’s opportunistic. He did not call this military exercise while the Olympics were still going on and made no aggressive moves while the eyes of the world were on Sochi. But he is moving now.

Update: Are you kidding me?