Updated

U.S. Secretary of State John Kerry says it would be "deeply troubling" if Russia or Hong Kong had adequate notice about Edward Snowden's plans to flee to a country that will grant him asylum and still allowed him leave.

Snowden, a former National Security Agency contractor and a self-admitted leaker of state secrets, fled from Hong Kong to Moscow on Sunday after the U.S. moved to extradite him to face espionage charges. He was expected to seek political asylum in Ecuador.

He was booked on a flight from Moscow to Cuba on Monday, but apparently was not on the plane. It was unclear where he was.

In the past two years, Kerry says, the U.S. has transferred seven prisoners to Russia that Moscow wanted.

The U.S. has revoked Snowden's passport.