Obama previously said 'he's not scrambling jets' to catch him, but given this week's events I don't believe him. I wouldn't at all be surprised if the US went after his flight somehow. It seems like this administration is willing to be the international villain in their attempts to catch Snowden.
And maybe the CIA wouldn't dare forcibly take Snowden out of Russia or China, but who's to say they wouldn't do so to a smaller, less powerful country?