This is a perfect moment for the crisis in Ukraine to heat up, and worrying developments are afoot, prompting fears that Russian President Vladimir Putin might be planning an invasion or some other kind of hostile action against Kiev after all.

On Aug. 10, Russia's secret police, the FSB, said it had prevented a series of terror attacks in Crimea and that one of its operatives and a Russian soldier were killed in several shootouts with what the FSB says were agents of the Ukrainian defense ministry's intelligence directorate. The FSB didn't elaborate on the foiled attacks, but said it had seized a cache of weapons and explosives and arrested a Ukrainian military intelligence operative named Yevgeny Panov.

The FSB announcement would normally be only moderately troubling. Russia has reported attempted Ukrainian terror attacks in Crimea before, though it has never directly blamed authorities in Kiev. But it was Putin's emotionally charged language that raised alarm bells: "The people who seized power in Kiev and who continue to hold on to it," he said, "have moved on to the practice of terror instead of looking for paths toward peaceful resolution."