Russia Strikes Ukraine’s Energy Sector as Putin Signals More to Come

Russia attacked Ukrainian energy infrastructure with missiles and drones on Thursday, in what President Vladimir V. Putin said was retaliation for Kyiv’s hitting Russian territory with long-range American missiles.

Mr. Putin suggested that such strikes could be stepped up, after millions of Ukrainians were left without power on Thursday, Ukrainian officials said. Ukraine’s energy ministry said it was the 11th major attack on the country’s energy infrastructure this year.

The total extent of the damage was not immediately clear, but explosions were heard in cities across Ukraine, and many officials reported power outages. Six people were reported injured across the country, according to the regional authorities.

“The energy sector is under massive enemy attack again,” Ukraine’s energy minister, Herman Halushchenko, wrote on his Facebook page. The operator of the Ukrainian transmission system “has urgently introduced emergency power outages,” he added.

Russia and Ukraine have been engaged in an escalating cycle of strikes against each other in recent weeks. While attacks on Ukrainian energy infrastructure have long been a tactic used by Russia, some analysts say both sides are also trying to improve their negotiating position before the inauguration of President-elect Donald J. Trump.

Mr. Trump has promised to end the conflict, without specifying how.

Speaking at a meeting of a Moscow-led security alliance in Kazakhstan, Mr. Putin warned that Russian strikes on Ukraine could intensify, saying that his country has been selecting targets for missile strikes in Kyiv, the Ukrainian capital, and that they might include “decision-making centers” there.