VLADIKAVKAZ, Russia » If anyone is still wondering why Russia finds itself entangled deeper and deeper in its attempt to pacify the Caucasus, Aslan Aushev, for one, would be happy to explain.

It was the spring of 2009. He had just left his family home in the Ingush central city of Nazran for work one morning when a column of armored personnel carriers manned by masked federal troops roared in and surrounded the house next door. Aushev, 23, rushed back and begged the federal officers to allow him to evacuate his family, including his 5-year-old sister, from the basement where they were cowering, thinking they would do him a favor because he is a police officer.

He was wrong. Aushev told the story in a tone of liquid hatred. The Russians made him stand spread-eagled against a wall for two hours, arguing about whether to shoot him. By the time the raid was finished, the trapped militants had killed themselves in a powerful explosion, but that barely registered with Aushev. His little sister emerged from the basement so terrified that, for the first time in her life, she was stuttering.

He said he would never look at Russians the same way.

“;They didn't respect my rank,”; he said in an interview the next day. “;From today on, I will never respect them.”;

Aushev's story says a great deal about the morass Russia has found itself in as it tried to stamp out the last remnants of resistance in the Caucasus, where another suicide bomber struck on Monday, killing two policemen. Violence has indeed receded since the beginning of the last decade, and the enemy — once powerful enough to drive the Russian Army out of Grozny — is incalculably weaker. But it is a dispersed and shadowy force, run in local cells protected by steel beams of clan loyalty.

Federal operatives have no way of knowing whom to trust. Opposition fighters might be the disheveled young fanatics evoked by Russian propaganda — or they could be local bureaucrats. Or policemen. And the more violence Russian forces use to hunt them down, the deeper the reservoir of hatred they leave behind.

“;It's almost impossible to fight the insurgency as it is today,”; said Mark Galeotti, a specialist in Russian security issues who leads New York University's Center for Global Affairs. “;Even when you're talking to officers in the FSB, you get a constituency that says, 'We're going to be facing these kinds of attacks as long as you have miserably unhappy, desperate people in the North Caucasus.”;' The FSB is Russia's security service.

The Caucasus mountain range forms a natural wall on Russia's southern border, and that is one reason leaders in Moscow, 900 miles to the north, have held the territory so jealously. It has been a bloody struggle; the highlanders are suspicious of outsiders and steeped in a tradition of warfare. After serving in the czar's army in the 19th century, Tolstoy described the Chechens' feeling toward Russians as something “;stronger than hatred,”; a gag reflex as natural as “;the desire to destroy rats, poisonous spiders and wolves.”;

Not so long ago, Vladimir Putin, then Russian president, seemed to have brought calm to Chechnya. Twice Russia went to war against the rebels, but Putin shifted his approach, subcontracting administration of the troubled region to a brutal local warlord, Ramzan A. Kadyrov, who swore fealty to Moscow.

Federal funds flowed into Kadyrov's treasury, and a shining city rose out of the squalor of post-war Grozny. Refugees returned, gazing in awe at paved roads and rows of housing blocks. Those still drawn to the rebellion, meanwhile, met with a campaign of terror: Men in ski masks drenched their houses with gasoline and tossed in torches. Kadyrov's paramilitary groups were accused of torture, kidnapping and extrajudicial killing.

But even as Moscow celebrated its success, the insurgency was morphing. Some of the rebels traded in their arms to join Kadyrov's apparatus, but others moved into the neighboring republics, like Ingushetia and Dagestan, where the local government was weaker. They traded in their old pursuit — a secular, independent state — for the more grandiose vision of a pan-Caucasian Shariah state. Old-fashioned military offensives were replaced by snipers, ambushes and a series of sickening terrorist attacks.

The new insurgents constructed their lives around secrecy.

“;I think they go to work during the day,”; said Sergei A. Arutyunov, a Caucasus expert at the Russian Academy of Sciences, who estimates the number of active militants at between 500 and 1,000. “;They are educated intelligentsia. They can remain in the shadows if they want. They could be officials who live a double life, or they could be in the police force.”;

Though some Russian leaders have suggested that poor living conditions in the Caucasus may fuel the violence, the Kremlin has often cast rebels as agents of foreign powers bent on breaking Russia apart. In any case, the government rarely seems to engage in self-questioning over its counterinsurgency tactics. Leaders are hunted down and killed, not brought to trial. Federal forces sometimes lay waste to whole neighborhoods in pursuit of a few fighters, and young men regularly disappear after they are picked up as terrorism suspects, leaving gaping holes in the center of families.

Mukhmed Y. Gazdiyev, a retired history teacher in the Ingush city of Karabulak, said he spent months petitioning regional officials after his 27-year-old son, Ibragim, was arrested by two men in camouflage uniforms. He was told his son was being held for interrogation. That was three years ago.

“;Already, as a father, I can't help my son anymore,”; Gazdiyev said grimly in an interview. “;I want to light myself on fire in Red Square. I am a tumor.”;

That does not mean that citizens in the Caucasus generally embrace radical Islam, nor that they approve of terrorist tactics. Arutyunov, who has studied the response to the insurgency in Dagestan, said no more than 10 percent of people there supported insurgent groups like the one led by Doku Umarov, who claimed responsibility for last week's bombing of the Moscow subway. But if militants are seeking to replenish the ranks of suicide bombers, he said, they will find a vast pool of young men and women who have lost siblings or friends in counterterrorist operations.

“;To find candidates is very easy,”; he said. “;There are 100,000 people here who are furious with the authorities.”;

A day after the federal raid in his neighborhood last year, Aushev, the young policeman, seemed ready to join that group.

He looked across at his neighbor's house, which was reduced to a crater and two blood-spattered kitchen walls when the trapped militants set off an estimated 440 pounds of explosives. He wondered why the FSB agents had not reached out to him, a fellow law enforcement officer, for intelligence about the neighborhood before they drove in with guns blazing. He would have helped, he said.

Something about Aushev's tone suggested that it was now too late. His cell phone held the text messages he had received from his family members trapped in the basement throughout the firefight. All that time he was begging the Russian officers to have pity on his family, and men in the Caucasus do not beg easily.

“;I told them there were children in there,”; he said flatly. “;They didn't listen.”;