Oleg Klimov / Getty Images A view of the general office of the FSB (KGB) building in Moscow

Say what you will about Julian Assange, founder of the whistle-blowing website WikiLeaks, but his work has shown him to be pretty fearless. After his site published the biggest cache of secret files in U.S. history on Oct. 22, detailing some of the ugly truths about the war in Iraq, he continued to travel around Europe despite U.S. reprimands and warnings. He even told the global media that new leaks would expose more secrets not only about the U.S. military but about other "repressive regimes," such as Russia and China. The signals coming from Moscow, however, suggest that the Russian reaction will not be as reserved as America's. So is WikiLeaks really ready to take on the world's more callous states?

It's certainly talking the talk. In an interview published on Tuesday, Oct. 26, in Russia's leading daily newspaper, Kommersant, WikiLeaks spokesman Kristinn Hrafnsson said that "Russian readers will learn a lot about their country" after one of the site's upcoming document dumps. "We want to tell people the truth about the actions of their governments." (See the top 10 leaks in history.)

So far Russia has had no official response. But on Wednesday, an official at the Center for Information Security of the FSB, Russia's secret police, gave a warning to WikiLeaks that showed none of the tact of the U.S. reply to the Iraq revelations. "It's essential to remember that given the will and the relevant orders, [WikiLeaks] can be made inaccessible forever," the anonymous official told the independent Russian news website LifeNews.

When reached by TIME, the FSB, which is the main successor to the Soviet KGB, declined to elaborate on the comment or say whether it was the agency's official position. But history has shown that the FSB readily steps in to shut down Internet tattlers. In June, a Russian analog to WikiLeaks called Lubyanskaya Pravda published a series of documents it claimed to be top-secret FSB files detailing the agency's operations in the former Soviet Union and conflicts with other Russian security forces. (Watch WikiLeaks' Julian Assange discuss TIME's top 10 leaks.)

The site stayed online for less than three weeks  during which time no Russian newspapers published the files  and then put up a notice saying it was under construction. With the site down and the people who anonymously ran it unreachable, the leak was apparently stopped. "The FSB could have easily found the people behind it and convinced them that this was not a good idea," says Andrei Soldatov, an expert on Russian security services. "It is also possible for the FSB to take down a site like WikiLeaks. They have the capacity for all of this."

In a far more gruesome case of leak patching, former FSB agent Alexander Litvinenko, who had published damning books about the agency and Russia's leadership, was poisoned with a rare and highly radioactive polonium isotope while living in London in 2006. British police suspect former Russian security agent Andrei Lugovoi of murdering Litvinenko. But the Russian government, which vehemently denies any connection to the murder, has refused to extradite Lugovoi, and a nationalist party has since made him a member of the Russian parliament. (See pictures of Russian police breaking up an anti-Kremlin rally.)

"If the FSB says it is capable [of taking out WikiLeaks], I believe them," says Gadi Evron, an expert on cybersecurity and counterespionage. It would not be necessary to crash the WikiLeaks site, says Evron, because "behind every Internet project, there are people." And people can be coerced  or worse. (Read TIME's 2007 piece on the launch of WikiLeaks.)

But other observers say WikiLeaks presents a far more serious challenge to Russia's security services than the sources of previous leaks. For one thing, WikiLeaks has established a reputation for publishing authentic documents, which means the Russian press would be more likely to cover the story and republish the files. It is also a diffuse and secretive organization that is technologically prepared to deal with cyberattacks. The kinds of hacker raids that took down Georgia's government websites during its war with Russia in 2008, for example, probably wouldn't keep WikiLeaks offline for long. (See pictures of Russian soldiers in Georgia.)

So the most likely Russian reaction, at least at first, would be to undermine the authenticity of the alleged secrets. "That is the main tool  to filter it through the state-controlled mass media, which would discredit WikiLeaks and put into question the reliability of its sources," says Nikolai Zlobin, director of the Russia and Eurasia Project at the World Security Institute in Washington, D.C. "This would limit any public debate of the leak to the Russian Internet forums and news websites, which reach a tiny fraction of the population."

Zlobin says it would also take something extremely damning to rattle Russia's political elite. "Russians already believe that their leaders steal, that they have offshore bank accounts and funnel money into them," he says. "It would have to give shocking details about the country's two leading figures [Prime Minister Vladimir Putin and President Dmitri Medvedev], and even then, the complete apathy toward politics in Russian society would absorb a lot of the shock waves at home." (See TIME's photo gallery "Vladimir Putin: Action Figure.")

Russia's reputation abroad, however, could be badly hit by the release of foreign-policy secrets. As the Kremlin pushes ahead with a drive to charm the West, its security agencies will be eager to prevent that kind of embarrassment. And there's no knowing how far they'll go to save face.

See pictures of Putin and Medvedev's ski vacation.