Russian President Vladimir Putin's decision to sign a bill that bars Americans from adopting Russian children provoked anguish Thursday 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 and 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 Russian children have been adopted by Americans, and officials said the measure will block the pending adoptions of 46 more.