MOSCOW — Donald Trump, the leading Republican presidential candidate, was widely condemned when he called for the United States to "take out the families" of terrorists.
His approach — even after he clarified that he was not talking about killing the relatives — was dismissed by many as immoral and unlawful. Yet, it is a tactic that Russia has pursued for decades.
It is the signature, though officially unacknowledged, policy behind Moscow's counterinsurgency and counterterrorism strategies, and Russia's actions in smashing a Muslim separatist rebellion in the Caucasus provide a laboratory for testing Trump's ideas.
The family ties that bind in terrorist groups came into focus last week after the police in Brussels disclosed that two of the three suicide bombers in the attacks there were brothers, Ibrahim and Khalid El Bakraoui. All told, analysts estimate that a third of the participants in terrorist acts are related to another attacker.
In the conflict that began in Chechnya and has since metastasized into a loosely organized Islamic rebellion throughout the Caucasus region, Russian security services routinely arrest, torture and kill relatives, rights groups say.
The Russian approach, enough to make supporters of waterboarding wince, has by some accounts been grimly effective. Abductions of family members unwound the rebel leadership in Chechnya, for example.
And siblings have a bloody track record here, as elsewhere.
In 2004, Chechen sisters blew themselves up in an airplane and a subway station a week apart. In 2011, the police say, a teenager and his older sister from Ingushetia, another troubled region, helped build a bomb that their brother exploded in the unguarded arrivals hall of Domodedovo Airport in Moscow, killing himself and 36 other people.
In the Russian view, the family is the thread that needs to be pulled to unravel the terrorist group.
"He should understand his relatives will be treated as accomplices," Kirill V. Kabanov, a member of President Vladimir Putin's human rights council, said of a potential suicide attacker.
"When a person leaves to become a terrorist, he can kill hundreds of innocents," he said. "Those are the morals we are talking about. We should understand, the relatives must fight this first. If the relative, before the fact, reported it, he is not guilty. If he did not, he is guilty."
In Chechnya and neighboring Dagestan, they routinely burn or demolish the houses of people suspected of being insurgents or terrorists. Most strikingly, whole extended families are rounded up in high-profile cases, and are often held until the militant either gives up or is killed.
Maryam Akmedova, from Kabardino-Balkaria region in the North Caucasus, has seen it firsthand. Distressing though it was, she says she understood when Russian prosecutors accused her eldest son of participating in a terrorist attack, as he had never denied his involvement.
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But her woes hardly stopped there.
Soon enough, security agents were questioning her younger son, though there was no evidence linking him to the attack his brother was accused of in the city of Nalchik in 2005. Eventually, the younger brother was shot and killed in 2013 by Russian security forces during an attempted arrest under murky circumstances.
"He had no involvement with anything," Akmedova said in a telephone interview. "They killed him because his brother was in prison."