Obama Suggests Putin Made 'Strategic Mistake'

US President Barack Obama has said Russia's President Vladimir Putin made a "strategic mistake" when he annexed Crimea, in a move that was "not so smart".

Those thinking his Russian counterpart was a "genius" had been proven wrong by Russia's economic crisis, he said in an interview for the US' National Public Radio.

International sanctions had made Russia's economy particularly vulnerable to changes in oil price, Obama said.

"You'll recall that three or four months ago, everybody in Washington was convinced that President Putin was a genius and he had outmanoeuvred all of us and he had bullied and strategised his way into expanding Russian power," he said.

"Today, I'd sense that at least outside of Russia, maybe some people are thinking what Putin did wasn't so smart."

The US President argued that sanctions had made the Russian economy vulnerable to "inevitable" disruptions in oil price which, when they came, led to "enormous difficulties".

"The big advantage we have with Russia is we've got a dynamic, vital economy, and they don't," he said. "They rely on oil. We rely on oil and iPads and movies and you name it."