MOSCOW (Reuters) - Russian Foreign Minister Sergei Lavrov said on Sunday he had detected increasing U.S. hostility towards Moscow and complained about what he said was a series of aggressive U.S. steps that threatened Russia's national security.

In an interview with Russian state TV likely to worsen already poor relations with Washington, Lavrov made it clear he blamed the Obama administration for what he described as a sharp deterioration in U.S.-Russia ties.

"We have witnessed a fundamental change of circumstances when it comes to the aggressive Russophobia that now lies at the heart of U.S. policy towards Russia," Lavrov told Russian state TV's First Channel.

"It's not just a rhetorical Russophobia, but aggressive steps that really hurt our national interests and pose a threat to our security."

With relations between Moscow and Washington strained over issues from Syria to Ukraine, Lavrov reeled off a long list of Russian grievances against the United States which he said helped contribute to an atmosphere of mistrust that was in some ways more dangerous and unpredictable than the Cold War.

He complained that NATO had been steadily moving military infrastructure closer to Russia's borders and lashed out at Western sanctions imposed over Moscow's role in the Ukraine crisis.

He also said he had heard that some policy makers in Washington were suggesting that President Barack Obama sanction the carpet bombing of the Syrian government's military air fields to ground its air force.

"This is a very dangerous game given that Russia, being in Syria at the invitation of the legitimate government of this country and having two bases there, has got air defense systems there to protect its assets," said Lavrov.

Lavrov said he hoped Obama would not agree to such a scenario.

Russia suspended a treaty with Washington on cleaning up weapons grade plutonium earlier this month in response to what it said were "unfriendly acts" by the United States.

Lavrov said both countries had the right to pull out of the treaty in the event of "a fundamental change in circumstances".

"The treaty was concluded when relations were normal, civilized, when no one ... was trying to interfere in the (other's) internal affairs. That's the fundamental change of circumstances," said Lavrov.

(Reporting by Maria Kiselyova; Editing by Andrew Osborn)