Russian President Vladimir Putin signed a bill Friday that bars Americans from adopting Russian children, provoking anguish among U.S. families that have been waiting months, and in some cases years, to complete the process.

The legislation caps a year of increasing Russian hostility toward the United States, stoked by Putin but taken up with unexpected gusto by members of parliament. A series of measures has taken aim at what is perceived to be — or characterized as — American interference in Russian concerns, from political organizing to the defense of human rights. The adoption bill is seen as retaliation against a U.S. law that targets corrupt Russian officials.

Passage of the legislation is a benchmark in the deterioration of Russian-American relations, and unlike some of the earlier, symbolic moves, it has real consequences. Over the past 20 years, 60,000 Russians have been adopted by Americans, and officials said the measure would block the pending adoptions of 46 children.

Kim Summers of Freehold, N.J., was just weeks away from bringing home her adopted son, Preston, when the legislation hit. She and her husband adopted him on Dec. 12 and returned to the United States three days later to complete a required 30-day waiting period.

“As far as we knew until this morning, he was coming home with us,” Summers said. “What’s going on has absolutely nothing to do with parenting a child. My son was looked at by 22 Russian families before I had the chance to even fathom adopting him, and none of them wanted him.”

See which countries the U.S. adopted from in 2011

Senior members of the Russian cabinet had warned against the bill, saying that it punishes orphans more than it does American politicians and that it looks like a defense of corruption while unavoidably drawing attention to the sorry state of Russian orphanages.

But Putin disregarded the warnings, seemingly pulled along by the enthusiasm for the legislation in both houses of parliament.

Washington reacted sharply to the new law Friday. The State Department issued a statement saying it deeply regrets “the Russian government’s politically motivated decision.” It also expressed hope that adoptive parents and children “who have already met and bonded” would be allowed to complete adoption procedures that were initiated before the law took effect.

Sen. John McCain (R-Ariz.) called Putin’s action “shameful and appalling” and said the law’s effects on thousands of Russian children would be “cruel and malicious.” He said in a statement: “I often wonder how much lower the Russian government under President Putin can stoop. But to punish innocent babies and children over a political disagreement between our governments is a new low, even for Putin’s Russia.”

The issues at the heart of the U.S.-Russian relationship in the coming year are critical to the United States, primarily the continuing transit of goods into and out of Afghanistan, and Russian cooperation on Iran. So far, both topics have been kept mostly out of the fray.

For several weeks, Putin appeared to be putting the brakes on the adoption ban. He raised questions about it at his annual news conference this month, and Foreign Minister Sergei Lavrov and Science and Education Minister Dmitry Livanov, among others, called it ill-advised. But on Thursday, Putin said, “I have not seen any reason why I should not sign it.”

The bill has elicited strong reactions from opposition figures, who view it as a case of Russia shooting itself in the foot. Journalist Alexander Minkin, on his blog for the Ekho Moskvy Web site, described it as “cannibalistic.” With Americans placing sanctions on certain corrupt Russian bureaucrats, he wrote, Moscow strikes back by punishing its own orphans.

The move abruptly cancels a painstakingly negotiated bilateral agreement regulating American adoptions of Russians. That agreement went into effect just weeks ago.

But Putin has described the agreement as ineffective and a case of “sham stupidity.”

The adoption law passed the lower house of parliament by a vote of 420 to 7 and passed the upper house unanimously.

Anti-American fervor

Putin began stepping up his anti-American rhetoric a year ago, as he was running for president. He accused Secretary of State Hillary Rodham Clinton of fomenting the street protests that took place in Moscow over the winter. Parliament then passed a law requiring nonprofit groups that receive foreign funds — which, in Russia’s case, primarily means American funds — to register as “foreign agents.” This fall, Putin ordered the U.S. Agency for International Development to close its Russian operation.

All year long, politicians in parliament and the Kremlin railed against the prospect that the U.S. Congress would pass a law in honor of the late whistleblower Sergei Magnitsky, targeting the corrupt Russian tax and police officials who had a hand in his case. After Congress passed the legislation, and President Obama signed it into law this month, Russia’s response was the adoption measure.

In a statement, State Department spokesman Patrick Ventrell said: “We have repeatedly made clear, both in private and in public, our deep concerns about the bill passed by the Russian parliament. . . . The welfare of children is simply too important to tie to the political aspects of our relationship.”

Putin said Thursday that he will issue decrees intended to improve conditions in orphanages and make adoption more palatable for Russian families. He noted approvingly that in some of the most violent regions of the Caucasus, children of those who have died are taken in by relatives, in contrast to the rest of the country.

The Russian government’s ombudsman for children, Pavel Astakhov, said the country can phase out all its orphanages in five to seven years. He said it should ban all foreign adoptions, not just those by Americans.

Ilya Yashin, a young opposition leader, said in a tweet that Astakhov’s position represented “cynicism beyond limits.” The newspaper Novaya Gazeta said 100,000 people had signed an online petition against the bill. The Putin-appointed Human Rights Council said the legislation punishes the innocent and opens up new ground for corruption.

Sarah Mraz, director of international adoption programs at Wide Horizons for Children, said the Massachusetts-based child-welfare organization spent the day counseling families.

“It has been very difficult for families to understand that politics can supersede the importance of a child to have a family,” she said. “It’s devastating to the families.”

The legislation would still allow Russian children to go to the United States if they are taken in by relatives, and critics suggested Thursday that interested couples would find ways to “buy” family connections.

The Magnitsky link

The Russian legislation also draws even more attention to the Sergei Magnitsky Rule of Law Accountability Act. That law places financial and visa sanctions on officials connected to the arrest, imprisonment and death of Magnitsky, a lawyer who unearthed a $230 million tax fraud and was subsequently arrested by the same police officers who he said were carrying out the fraud. He died in jail in 2009. According to his supporters, he had just been given a severe beating.

That tax fraud involved senior officials of the tax agency as well as police. Hermitage Capital, Magnitsky’s client, has tracked millions of dollars of overseas financial transfers by those officials and uncovered other, similar cases.

A Moscow judge on Friday acquitted prison doctor Dmitry Kratov, the only person to face trial in the Magnitsky case, finding no evidence of negligence leading to the lawyer’s death. The acquittal was requested by the prosecution after Putin said publicly a week ago that “no one tortured Magnitsky, and he died of heart failure.”

“There is no doubt that people responsible for Magnitsky’s death are being protected by the president of Russia,” the Britain-based Hermitage Capital said in a statement Friday.

The American law named for Magnitsky struck a nerve with Russian officials, who have denounced it. Legislators named their retaliatory bill the Dima Yakovlev law, after a Russian toddler who died in Virginia when his adoptive father left him unattended in a locked car on a hot July day. The father was later acquitted of charges of involuntary manslaughter, sparking strong Russian criticism.

According to the U.S. Embassy in Moscow, 19 Russian adoptees have died in the United States in the past 20 years.