Russian President Vladimir Putin’s habitual bullying of grown-ups was bad enough.

Now he’s picking on helpless kids.

Mr. Putin signed legislation on Friday prohibiting Americans’ adoption of Russian children. The new law was written in retaliation to a congressional bill, signed into law by President Barack Obama on Dec. 14, that bars Russians accused of human-rights abuses from entering the U.S.

In other words, Russia’s repressive government is defending its abysmal human-rights record by denying Russian orphans in grim circumstances the right to be adopted by American parents who would provide loving care for them.

As Reuters reported Friday: “Fifty-two children whose adoptions by American parents were under way will remain in Russia.”

The Russian law, which takes effect Tuesday with the start of the new year, also will ban some organizations that receive U.S. funding — and impose visa and asset freezes on Americans accused of “violating the rights of Russians abroad.” The U.S. law that prompted this Russian outrage is the Magnitsky Act, named for a lawyer who died in a Moscow jail in 2009 after being beaten while confined there.

Mr. Magnitsky was officially charged with fraud — despite being an ardent foe of corruption. The Russian “justice” system is even moving forward on trying him posthumously. Such an Orwellian development might be the only way that the government can reasonably count on a conviction.

On Friday, a Russian court acquitted Dmitry Kratov, the only defendant in the case of Mr. Magnitsky’s death.

As for the adoption ban, consider the vast scale of its negative impact: According to UNICEF, about 740,000 Russian children are in state care — and fewer than 7,000 per year are adopted by Russian families.

U.S. State Department spokesman Patrick Ventrell stated the sadly obvious: “Since 1992 American families have welcomed more than 60,000 Russian children into their homes, and it is misguided to link the fate of children to unrelated political considerations.”

It is also misguided to put much faith in President Obama’s hopes of what he has called a “reset” of America’s strained relationship with Russia as long as Mr. Putin remains in charge.

And anybody who doubts that reality should ponder the utter cruelty that the new Russian law imposes on innocent children in need.