The initial government response was muted, with Dmitri S. Peskov, the spokesman for Mr. Putin, telling reporters that “it would be wrong to make hasty decisions” and predicting that the value of the ruble and the Russian stock market would bounce back once emotions settled down.

Given the tiny size of the Russian economy — around 2 percent of global G.D.P. — and its limited trade with the United States, there was little expectation of economic retaliation. Any Russian response was likely to come in places like Syria or Ukraine, analysts said, where the Kremlin might ratchet up tensions in order to leverage any solution on ending the sanctions.

With an American strike in Syria possible at any moment, in response to what was suspected to be a chemical weapons attack by the forces of President Bashar al-Assad, an occasion for that scenario might materialize quickly.

Russia had been lulled into thinking no significant sanctions were coming. In January, in response to a new United States law last summer demanding tougher action against Moscow, the Trump administration did nothing more than publish a list culled from the pages of Forbes Magazine of every billionaire in the country along with the Kremlin’s internal telephone directory.

“People thought this was a joke, but now it is clear that the situation is serious,” said Vladislav S. Zhukovsky, an economist and investment consultant. “This is more serious than the previous sanctions.”

The two most prominent industrialists targeted were Mr. Deripaska, whose Rusal company employs an estimated 60,000 in Russia, and Viktor F. Vekselberg, one of the richest men in Russia, whose projects include trying to develop the country’s tech sector.