MOSCOW — President Vladimir V. Putin of Russia emphasized on Thursday that the upper chamber of Parliament had authorized him to use military force if necessary in eastern Ukraine, and he asserted Russia’s historical claim to the territory in language not often used before, signaling a new and more aggressive policy.

Mr. Putin repeatedly referred to eastern Ukraine as “New Russia” — as the area north of the Black Sea was known after it was conquered by the Russian Empire in the late 1700s. He said only “God knows” why it became part of Ukraine in 1920.

Speaking in a televised question-and-answer show, Mr. Putin also admitted for the first time that Russian armed forces had been deployed in Crimea, the disputed peninsula Russia annexed last month immediately after a large majority of the population voted in a referendum to secede from Ukraine. But he dismissed suggestions that Russian troops were behind the unrest in eastern Ukraine.