The International Criminal Court on Friday issued an arrest warrant for President Vladimir V. Putin of Russia for war crimes, saying that he bore individual criminal responsibility for the abduction and deportation of Ukrainian children since Russia’s invasion last year.

The likelihood of a trial while Mr. Putin remains in power appears slim, because the court cannot try defendants in absentia. But human rights groups hailed the warrant as an important step toward ending impunity for Russian war crimes in Ukraine.

“The crimes were allegedly committed in Ukrainian occupied territory at least from 24 February 2022,” the court said in a statement, citing the month that Russia began its full-scale invasion of Ukraine.

The I.C.C. does not recognize immunity for heads of state in cases involving war crimes, crimes against humanity or genocide.

The Kremlin has denied accusations of war crimes, but has not been secretive about the transfers of Ukrainian children to Russia, depicting them as adoptions of abandoned children and promoting the program as a patriotic and humanitarian effort.

“This is a big day for the many victims of crimes committed by Russian forces in Ukraine since 2014,” said Balkees Jarrah, the associate director for international justice at Human Rights Watch. “With these arrest warrants, the I.C.C. has made Putin a wanted man and taken its first step to end the impunity that has emboldened perpetrators in Russia’s war against Ukraine for far too long.”

On Wednesday, a United Nations commission of inquiry said that Russia’s transfer of children and other civilians from Ukraine to Russia may amount to a war crime, observing that none of the cases they investigated were justified under international law. Ukraine has reported the transfer of 16,221 children to Russia, but the commission said it had not been able to verify the number.

Separately, large numbers of children were moved from areas occupied by Russian forces to so-called vacation camps in Crimea and inside Russia with parental consent, they noted, but Russia required parents to travel in person to collect them and many had been unable to do so, raising fears of permanent separation.