Putin said it is premature to talk about what Russia would do if the U.S. attacked Syria.
"We have our own ideas about how we would act in the case that chemical weapons were used or in the case that they weren't," he said. "We have our plans, but it's too early to talk about that."
Putin called the S-300 air defense missile system "a very efficient weapon" and said that Russia had a contract for its delivery of the S-300s to Syria. "We have supplied some of the components, but the delivery hasn't been completed. We have suspended it for now," he said.
"But if we see that steps are taken that violate the existing international norms, we shall think how we should act in the future, in particular regarding supplies of such sensitive weapons to certain regions of the world."
The statement could be a veiled threat to revive a contract for the delivery of the S-300s to Iran, which Russia canceled a few years ago under strong U.S. and Israeli pressure.
Putin praised Obama as a frank and constructive negotiating partner and denied reports that he had taken personal offense at remarks by Obama comparing Putin's body language to that of a slouching, bored student. Putin said appearances can be deceiving.
Putin also accused U.S. intelligence agencies of bungling efforts to apprehend Snowden, the National Security Agency leaker, who is wanted in the U.S. on espionage charges. He said the United States could have allowed Snowden to go to a country where his security would not be guaranteed or intercepted him along the way, but instead pressured other countries not to accept him or even to allow a plane carrying him to cross their airspace. Russia has granted him temporary asylum.
Putin also gave the first official confirmation that Snowden had been in touch with Russian officials in Hong Kong before flying to Moscow on June 23, but said he learned that Snowden was on the flight only two hours before it arrived. Putin once again denied that Russia's security services are working with Snowden, whose stay in Russia has been shrouded in secrecy.
On another topic, he denied at length charges that Russia has anti-gay policies, indicating that Obama is welcome to meet with gay and lesbian activists in Russia during his visit. He said he might even meet with a similar group himself if there is interest from the Russian gay community.
Putin rejected criticism of the gay propaganda law, which prompted some activists to call for the boycott of the 2014 Winter Games in Sochi, arguing that it won't infringe on the rights of gays.
He also said that athletes and activists will not be punished if they raise rainbow flags or paint their fingernails in rainbow colors at the Feb. 7-23 Olympics.
But he clearly has no intention of allowing a gay pride parade or other such actions: Last month, Putin signed a decree banning all demonstrations and rallies in Sochi throughout the Winter Games.
As for the body language between Putin and Obama that some have said suggested a difficult working relationship, the Russian president urged everyone to avoid jumping to conclusions.
"There are some gestures, of course, that you can only interpret one way, but no one has ever seen those kinds of gestures directed by Obama at me or by me at Obama, and I hope that never happens," he said.
"Everything else is fantasy."
-By the Associated Press' John Daniszewski, Lynn Berry and Vladimir Isachenkov. AP writer Laura Mills in Moscow contributed to this report.