On Thursday night, the best assessment from the U.S. intelligence community—and for that matter most experts observing events in Ukraine—was that Vladimir Putin’s military would not invade Ukraine. Less than 24 hours later, however, there are reports from the ground of Russian troops pushing into the Ukrainian province of Crimea. It’s hardly a full-blown invasion. But it’s not quite the picture U.S. analysts were painting just a day before.

There was good reason to think Putin wouldn’t do it. Russia’s Foreign Minister, Sergei Lavrov told Secretary of State John Kerry that Russia respected the territorial integrity of the Ukraine. U.S. intelligence assessments concluded that the 150,000-man Russian military exercises announced by Putin on Wednesday were not preparations for an invasion of Ukraine because no medical units accompanied the troops. And Russian and U.S. diplomats were still working on Iran and Syrian diplomacy. All of this followed a successful Winter Olympic games for Putin’s Russia.

Yet private security contractors, working for the Russian military, seized control of two airports in Crimea on Friday. And Ukrainian border officials said that Russian cargo planes had landed inside the province, and that 10 military helicopters flew into Ukrainian airspace.