(ABC News) -- One American diplomat's tires were slashed. Another's personal email was hacked. Still others reported mysterious break-ins.
The incidents are all signs, U.S. officials and experts said, that aggressive, Soviet-era counterintelligence tactics are back in fashion in Russia.
The number of incidents targeting American diplomats in Moscow has increased in recent years to levels not seen since the Cold War, officials said. Taken together, they paint an escalating pattern of intimidation and harassment that is believed to be led by Russia's Federal Security Services (FSB), a successor to the Soviet KGB.
The trend has alarmed officials back in Washington, who have complained about the treatment to Russian officials at the highest levels, including President Vladimir Putin.