Former world chess champion and pro-democracy activist Garry Kasparov grabbed headlines earlier this week when he described Russian President Vladimir Putin as "the most dangerous man in the world."
He made the remark during an interview with Yahoo News, adding that Putin is "a greater threat to the United States than the Islamic State."
Later, Kasparov explained his characterizations during an interview with the host of VOA's Press Conference USA, Carol Castiel, in New York.
"It's a permanent threat," Kasparov told VOA.
'Cannot be defeated militarily'
Unlike the current outbreak of Ebola, Syria or even al-Qaida, Kasparov said, those crises can in the end be defeated, no matter how costly.
"When you look at Putin, he cannot be defeated militarily. Russia is second nuclear power in the world," he said. "So that's why the moment that you recognize that Putin is a threat, you have to deal with a very different kind of dilemma because now you have to look for a very comprehensive solution that will engage Russia, potentially China, and that puts the problem to a very, very different level."
To Kasparov, Putin is a dictator who is defiling "the fundamental values of the free world."
"The same way we call Saddam Hussein or General Pinochet or North Korean dictators, he [Putin] is a dictator who has no way out," he said. "He must stay in power."
The chess pro also had some tough words for the Obama administration's response to Putin's annexation of Crimea and the backing of separatists who are roiling eastern Ukraine.
Both the United States and the European Union have steadily ratcheted up sanctions on Russia.
"The policies imposed by the Western countries today, it's better than nothing," he said. "But it's still far from enough to prevent Putin from further aggression."
To stop Putin or any other problematic leader, Kasparov said he believes the U.S. president must strike a delicate balance: pose a credible threat without using force.
And he said the failure of both the Bush and Obama administrations to do that has created a dangerous vacuum by destroying "the credibility of the Oval Office."
"One wanted to use force all the time, the other one doesn't want to use force," Kasparov said. "Obama has been drawing red lines, one after another, and reneging on them. History shows that weakness eventually leads to a much bigger disaster."
How to deal with Putin?
So how would he deal with Putin?
Exploit what Putin believes is the Russian public's growing distaste for the war Ukraine, Kasparov said.
And if the "price of Crimea" becomes too steep and begins to bite ordinary Russians, Kasparov believes Putin might face a very serious - and new - domestic challenge.
"This challenge, as in the 1980's, cannot be cannot be successful without mounting pressure from the outside," he said.
"If sanctions in this format can be sustained until March , that will be the most serious challenge to Vladimir Putin's power and maybe still will offer a glimpse of hope that the change in Russia will not be as bloody as before," Kasparov said.