Spy Story: Little Fish With a Big Enemy

MOSCOW — Sergei V. Skripal was a little fish.

This is how British officials now describe Mr. Skripal, a Russian intelligence officer they recruited as a spy in the mid-1990s. When the Russians caught Mr. Skripal, they saw him that way, too, granting him a reduced sentence. So did the Americans: The intelligence chief who orchestrated his release to the West in 2010 had never heard of him when he was included in a spy swap with Moscow.

But Mr. Skripal was significant in the eyes of one man — Vladimir V. Putin, an intelligence officer of the same age and training.

The two men had dedicated their lives to an intelligence war between the Soviet Union and the West. When that war was suspended, both struggled to adapt.

One rose, and one fell. While Mr. Skripal was trying to reinvent himself, Mr. Putin and his allies, former intelligence officers, were gathering together the strands of the old Soviet system. Gaining power, Mr. Putin began taking revenge, reserving special hatred for those who had betrayed the intelligence tribe when it was most vulnerable.

Six months ago, Mr. Skripal was found beside his daughter, Yulia, slumped on a bench in an English city, hallucinating and foaming at the mouth. His poisoning led to a Cold War- style confrontation between Russia and the West, with both sides expelling diplomats and wrangling over who tried to kill him and why.

On September 5, British officials offered specifics, accusing Russia of sending two hit men to smear Mr. Skripal’s front door handle with a nerve agent, an accusation vigorously denied by Moscow. British intelligence chiefs claim they have identified the men as members of the same Russian military intelligence unit, the G.R.U., or Main Intelligence Directorate, where Mr. Skripal once worked.

It is unclear if Mr. Putin played a